But seek first His kingdom and His righteousness: zeteite (2PPAM) de proton ten basileian [tou theou] kai ten dikaiosunen autou (1 Kings 3:11-13; 17:13; 2 Chronicles 1:7-12; 31:20,21; Proverbs 2:1-9; 3:9,10; Haggai 1:2-11; 2:16-19; Luke 12:31; John 6:27) (Mt 3:2; 4:17; 13:44-46; Acts 20:25; 28:31; Romans 14:17; Colossians 1:13,14; 2 Thessalonians 1:5; 2 Peter 1:11)

But (1161) makes the contrast with the Gentiles. Jesus is saying rather than being like the pagans who are concerned about their physical needs, the citizens of the Kingdom of Heaven should be concerned about and seek after the things of God.

Seek first His kingdom - He does not say seek for the kingdom which is what Jesus would have said if He was addressing this command to unbelievers. Seek for it to get into it was not what He was saying. He was speaking to those who are kingdom citizens to make the interests of God's kingdom their priority. Kingdom citizens should ponder "Is what I am going to say or do going to advance God's kingdom and glory?"

Spurgeon writes that...

When I had resolved to enter college, walking across Midsummer Common, just outside of Cambridge, revolving in my mind the joys of scholarship and the hope of being something in the world, that text came to my heart,

"Seekest thou great things for thyself? Seek them not" (Jer. 45:5)

"Seek first the kingdom of God and his righteousness, and all these things shall be added unto you."

All was given up, everything was renounced, the finest pros­pects seemed to melt into thin air, merely on the strength of that text, believing that God would most certainly fulfill to me his promise if I could keep his precept.

God will always keep His word to the letter. Actually He will usually go beyond what the letter seems to mean. In this instance (cf "And the LORD gave Solomon wisdom, as he promised him" 1 Kings 5:12), while He gave Solomon wisdom, He also added to him riches and a thousand other things which did not appear in the compact.

Seek ye first the kingdom of God and His righteousness, and all these things shall be added unto you (Matt. 6:33).

He who makes promises about infinite blessings will throw in everyday things as if they were of small account and were given in as a matter of course, like the grocer’s paper bags in which he packs up our purchases.

Seek (2212) (zeteo) means to try to learn where something is or try to find as a searching for what is lost seek. To attempt to learn something by careful investigation or searching. Seeking in the present context speaks of a single minded focus, as when one's eye is "single" (clear) (see notes Mt  6:22-23)

Zeteo is in the present imperative so what Jesus is saying is that the antidote to worrying is to make a daily choice to prioritize God's kingdom and righteousness. Make it the habit of your life to prioritize seeking God's Kingdom and righteousness.

Notice then that Jesus is not suggesting but commanding all citizens of the Kingdom of heaven who still live on earth to cease making material things the center of their life ("stop worrying" Mt 6:25-32). Instead the believer's lifelong pursuit is not for things but the presence, pleasure and Person of Jesus Christ our Lord and our King ("kingdom" always indicates a "king"). See related resource by Anne Ortlund - Fix Your Eyes on Jesus

Dear Lord, may the words of Johnson Oatman's great hymn be our soul's deepest desire...

Higher Ground
I’m pressing on the upward way,
New heights I’m gaining every day;
Still praying as I’m onward bound,
“Lord, plant my feet on higher ground.”

Refrain
Lord, lift me up and let me stand,
By faith, on Heaven’s table land,
A higher plane than I have found;
Lord, plant my feet on higher ground.

My heart has no desire to stay
Where doubts arise and fears dismay;
Though some may dwell where those abound,
My prayer, my aim, is higher ground.
Refrain

I want to live above the world,
Though Satan’s darts at me are hurled;
For faith has caught the joyful sound,
The song of saints on higher ground.
Refrain

I want to scale the utmost height
And catch a gleam of glory bright;
But still I’ll pray till Heav’n I’ve found,
“Lord, plant my feet on higher ground.”
Refrain

In Mt 6:25-24 what Jesus has done is reduce what we seek for to effectively two categories, the essentials of life versus God's Kingdom and righteousness. Seeking for the former will make us anxious and worried. Seeking for God will give us peace that passes human understanding.

Jesus gives God's key to open the door to freedom from worry and anxiety - make the conscious, volitional choice every day of your life that your thoughts and actions will demonstrate that the kingdom of God is your priority in this world which is passing away.

Have you every heard of "worry beads" (fidget beads or komboloi [from kombos = knot or large number of knots + loi = a group that sticks together] in modern Greece - look it up in Google) which is a string of beads that when fingered or played with supposedly relieves nervous tension? You can get them at some great prices on EBay but they don't work! However Jesus' powerful teaching beginning in Matthew 6:25 and culminating in His command in Matthew 6:33 is the truth that can set you free if diligently "fingered" (i.e., mediated upon  and put into daily practice).

What Jesus is saying is that in essence "What you seek, you find." This principle reverberates throughout the Bible...

But from there you will seek the LORD your God, and you will find Him if you search for Him with all your heart and all your soul. (Deut 4:29)

As for you, my son Solomon, know the God of your father, and serve Him with a whole heart and a willing mind; for the LORD searches all hearts, and understands every intent of the thoughts. If you seek Him, He will let you find Him; but if you forsake Him, He will reject you forever. (1Chronicles 28:9)

R C Sproul explains that...

Seeking demands an intensity, a perseverance that will not be denied, and a zeal to achieve the desired objective. In addition to refocusing your goal of righteousness, allow the Scriptures to speak to your motivation and commitment. (Sproul, R. Vol. 1: Before the Face of God: Baker Book House; Ligonier Ministries)

J R Miller (Biography) wrote that...

We need have only one care, that we put the first thing first—faithfulness to God. Then all else we need for both worlds will be supplied. God will never fail us; but we forget, sometimes, in our rejoicing over such an assurance, that we must fulfill our part if we would claim the divine promise.

It will not always be easy. Tomorrow it may mean a distasteful task, a disagreeable duty, a costly sacrifice for one who does not seem worthy. Life is full of sore testings of our willingness to follow the Good Shepherd. We have not the slightest right to claim this assurance unless we have taken Christ as the guide of our life.

First (4413) (proton from protos = leading, foremost, prominent, most important) means first in time, place, order, importance. The word first indicates one’s first and ever dominant concern. 

The concept of “seeking first” for the things of God is a predominant biblical concept that touches one's motivation and priorities including how one spends their "leisure" time, the goals one sets in their life, and whether or not they experience spiritual growth.

What do you “seek first”? If you are like me, then people, possessions, power, prestige, pleasure, and other desires compete for your priority. All of these things can quickly bump God out of first place if we don’t actively choose to give Him first place in every area of life. A good way to begin each day is by declaring Romans 12:1 (see note Romans 12:1) and then living out the rest of that day as a "living sacrifice".

It is interesting that Jesus does not say we are to refrain from pursuing the material treasures of this world, but that we are replace those desires with a pursuit that has far greater significance in this life and the life to come.

What does it mean to pursue God's righteousness? One aspect is surely to submit to God's will that His children live righteously as described in the beatitudes - poor in spirit, mourning over sin, meek in spirit, hungering and thirsting for righteousness, etc. In a word this pursuit equates with sanctification or present tense salvation (see discussion of the Three Tenses of Salvation)

Barnhouse gives a practical illustration of what this righteousness looks like in a kingdom citizen...

A butcher was once asked what difference it made to him when Christ entered his life. He replied, “I stopped weighing my thumb.” He then told how, before becoming a Christian, he put meat on the scales in such a way that his thumb trailed down, approximately the weight of an ounce. He had included that thumb in the weight of beef, pork, lard, and every other item of his merchandise. But after Christ came into his heart, he stood away from the scales and gave a full sixteen ounces of meat. And when he served customers whom he had formerly cheated, he added an ounce to make up for past peculations. The Kingdom of God produces complete integrity in a believer.  (Barnhouse, D. G. God's Glory : Romans 14:13-16:27. Page 13. Grand Rapids, MI.: William B. Eerdmans Publishing Company)

Charles Spurgeon tells the story of a young man who openly confessed his decision to trust Christ. This decision sorely offended his father, who advised him,

“James, you should first get yourself established in a good trade, and then think of the matter of religion.”

“Father,” said the son, “Jesus Christ advises me differently; He says, ‘Seek ye first the kingdom of God’ “ (Matt. 6:33).

Lord of the cloud and fire,
I am a stranger, with a stranger's indifference;
My hands hold a pilgrim's staff,
My march is Zionward,
My eyes are toward the coming of the Lord.
--Old Puritan prayer.

In Faith's Checkbook, Spurgeon has a devotional on Mt 6:33 entitled God First, Then Extras...

SEE how the Bible opens: “In the beginning God.” Let your life open in the same way. Seek with your whole soul, first and foremost, the kingdom of God, as the place of your citizenship, and His righteousness as the character of your life. As for the rest, it will come from the Lord Himself without your being anxious concerning it. All that is needful for this life and godliness (see note 2 Peter 1:3) “shall be added unto you.”

What a promise this is! Food, raiment, home, and so forth, God undertakes to add to you while you seek Him.

You mind His business,
and He will mind yours.

If you want paper and string, you get them given in when you buy more important goods. And just so, all that we need of earthly things we shall have thrown in with the kingdom. He who is an heir of salvation shall not die of starvation, and he who clothes his soul with the righteousness of God cannot be left of the Lord with a naked body. Away with anxious care. Set all your mind upon seeking the Lord (see notes Colossians 3:1; Colossians 3:2).

Covetousness is poverty, and anxiety is misery:
Trust in God is an estate,
and likeness to God is a heavenly inheritance.

Lord, I seek thee, be found of me.

John Stott sums it up...

“In the end, just as there are only two kinds of piety, the self-centered and the God-centered, so there are only two kinds of ambition: one can be ambitious either for oneself or for God. There is no third alternative.” (Stott, John: The Message of the Sermon on the Mount: 1985, Intervarsity Press)

Constable asks and answers an interesting question....

 In view of this promise how can we explain the fact that some committed believers have perished for lack of food? There is a wider sphere of context in which this promise operates. We all live in a fallen world where the effects of sin pervade every aspect of life. Sometimes the godly, through no fault of their own, get caught up in the consequences of sin and perish. Jesus did not elaborate this dimension of life here but assumed it as something His hearers would have known and understood. (Tom Constable's Expository Notes on the Bible)

A QUESTION OF PRIORITIES...
WHERE DO YOU SPEND
YOUR TIME AND MONEY?

Pastor Ray Pritchard offers some insights on seeking writing that...

Everyone seeks something. We are all by nature seeking people. Some people seek for money, others for fame, others for pleasure, others for self-validation, others for sexual fulfillment, and others for worldly power. We may seek a husband or a wife or we may seek children or a new job or a better education or a new home or new friends or a new church. The tragedy of our time is that so many people are wasting their lives chasing after three things that can never satisfy—money, sex and power. We want money, so we sacrifice our families to get it. We want sex so we sacrifice our morals to get it. We want power so we sacrifice our friends to get it. And when we finally get it, it doesn’t satisfy...

Here’s a simple test to help you discover what you truly seek in life. This test is absolutely foolproof. You tell me how you spend your time and your money and I’ll tell you what you are seeking. You can say anything you like, you can come to church and look very religious, but your time and your money don’t lie. Time is life and money is nothing but the time it takes to make the money. Show me your calendar and your checkbook and I’ll know the truth about your priorities.

This week I read about a man who looked at his life and concluded that he was just like the Professor on Gilligan’s Island. “The Professor knew how to turn banana peels into diesel fuel and he could take algae and make chocolate fudge, but he never got around to fixing that hole in the boat so he could get off the island. Same as me. I spent my life learning to do amazing things that didn’t matter, and I ignored the hole in my boat. And that’s why I’m stuck where I am.”...

If you want righteousness, you can have it. Let me go out on a limb and make a bold statement. Whatever righteous thing you desire in the spiritual realm, you can have if you want it badly enough. I don’t think we appreciate the importance of that truth. Most of us are about as close to God now as we want to be. We have about as much joy as we want, about as much peace as we want. Abraham Lincoln said that “most people are about as happy as they want to be.” Totally true. We are the way we are because that’s the way we want to be. Either we’re happy that way or we’ve accepted that this is who we are and we’re not going to change. For the most part, you are where you are right now because that’s where you want to be. If you were hungry for something better from God, you could have it....

What we seek, we find. This is true in every area and realm of life. Unless we seek, we will not find. And what we seek, for good or for ill, we eventually find. (Matthew 6:33 The Fourth Law: What You Seek, You Find)

Are you a God seeking person? Do you really want to know? Ask a brother or sister in Christ? Or better yet ask an unsaved person who knows you. They many not know the Scriptures like you do but you may be surprised at their answer. If the answer surprises you and you discover others don't see you as a God seeker, consider Pastor Pritchard's five suggestions to stimulate your seeking first God's kingdom and His righteousness...

First, admit your need. You cannot change until you admit that you need to change. If you are happy the way you are, then I have nothing to do say to you. But if you are tired of turning banana peels into diesel fuel while there’s a hole in your boat, then pay attention because your life could be radically changed.

Second, cry out to God for help. Early on Sunday morning I met a man who said, “It happened 16 years ago today.” What happened? “Sixteen years ago my life hit rock bottom. Alcohol had destroyed me. My marriage was gone, my career was ruined, and my life was a wreck. I had tried everything the world had to offer and nothing seemed to make a difference. When I finally had nowhere else to turn, I cried out to Jesus. Sixteen years ago today, he heard my cry and changed my life.” That man was in our early worship service on Sunday. He is living proof of the life-changing power of Jesus Christ. He cried out and the Lord heard him and saved him from the pit of destruction. If you need the Lord, cry out to him today. Seek him with all your heart and you will find him.

Third, surround yourself with God-seeking people. You know who they are. God-seekers aren’t hard to spot. Find some friends who truly seek the Lord and glue yourself to them. Go where they go, do what they do. Follow their example. Eventually one of two things will happen. Either they will drive you nuts and you will leave them or they will rub off on you and you will become a God-seeker too.

Fourth, wait on the Lord. This is a hard discipline for most of us to practice. Our message to God is, “Give me patience, and give it to me right now!” We want spiritual maturity and we want it by 11:30 a.m. We’re not accustomed to waiting patiently on the Lord. But waiting has many positive benefits. The very act of waiting purifies our hearts and increases our longing to know the Lord intimately. As we wait and as we pray, we become like the deer panting for the water. Our souls grow hungry to know the Lord.

Fifth, spend time in fasting. I believe there is a direct connection between biblical fasting and seeking the Lord. For some, that might mean going without a meal once a week in order to wait on God. For others, it might mean going a day without a meal. The ancient discipline of biblical fasting can be practiced many different ways. I have found it beneficial to take a day a week and fast from sunrise to sundown. And on occasion I have fasted for several days at a time. Fasting slows us down, reorients our perspective, weans us away from our love of the world, and puts us in a spiritual position where we can seek God with fewer distractions. (If you would like instruction in this area, I highly recommend the book A Hunger for God by John Piper from Crossway Books.) (Ed note: A Hunger for God is available free online. Also see notes on fasting from Matthew 6:16-18)

The great mystic Thomas a Kempis (who wrote The Imitation of Christ) said, “Seek God, not happiness.” We have it all backwards. We seek happiness and hope to have God thrown in as a bonus. But we end up with neither. The paradox of the gospel is that when we truly seek God, we find him, and we get happiness (deep fulfillment, lasting joy, the abundant life) too. But it takes years for many of us to figure that out, and some of us never get it straight. To the very end, we pursue earthly happiness and our own agendas and we wonder why life leaves us frustrated and disillusioned. (Matthew 6:33 The Fourth Law: What You Seek, You Find)

David encourages us...

O fear the LORD, you His saints; For to those who fear Him, there is no want. The young lions do lack and suffer hunger; But they who seek the LORD shall not be in want of any good thing. (Psalms 34:9,10) (Spurgeon comments: "Jehovah will not allow his faithful servants to starve. He may not give luxuries, but the promise binds him to supply necessaries, and he will not run back from his word. Many whims and wishes may remain ungratified, but real wants the Lord will supply. The fear of the Lord or true piety is not only the duty of those who avow themselves to be saints, that is, persons set apart and consecrated for holy duties, but it is also their path of safety and comfort. Men seek a patron and hope to prosper; he who has the Lord of Hosts to be his friend and defender prospers surely. They are fierce, cunning, strong, in all the vigor of youth, and yet they sometimes howl in their ravenous hunger, and even so crafty, designing, and oppressing men, with all their sagacity and unscrupulousness, often come to want; yet simple-minded believers, who dare not act as the greedy lions of earth, are fed with food convenient for them. No really good thing will be denied to those whose first and main end in life is to seek the Lord.)

The LORD knows the days of the blameless; And their inheritance will be forever. 19 They will not be ashamed in the time of evil; And in the days of famine they will have abundance...25 I have been young, and now I am old; Yet I have not seen the righteous forsaken, Or his descendants begging bread. (Ps 37:18,19,25) (Spurgeon comments: "None can deprive them of it, and none shall destroy it. What they have on earth is safe enough, but what they shall have in heaven is theirs without end... Their bread will be given them. Our Lord stayed himself on this when he hungered in the wilderness, and by faith he repelled the tempter. If God’s providence is our inheritance, we need not worry about the price of wheat. Faith, if it do not preserve the crop, can do what is better, namely, preserve our joy in the Lord.")

and all these things will be added to you: kai tauta panta prostethesetai (3SFPI) humin (Mt 19:29; Leviticus 25:20,21; Psalms 34:9,10; 37:3,18,19,25; 84:11,12; Mark 10:30; Luke 18:29,30; Romans 8:31; 1 Corinthians 3:22; 1 Timothy 4:8)

All (3956) (pas) means all without exception and in context all "these things", the things we "need" (not greed) to live this life for the glory of our Father Who art in heaven.

Added (4369) (prostithemi from prós = to or besides + títhemi = put) means to add something to an existing quantity. We have food and clothing for today but God will add necessary essentials in the future as the need arises. When our priority is spiritual, God will take care of the material, for where God guides, He provides.

Elsewhere Jesus declared...

"Truly I say to you, there is no one who has left house or brothers or sisters or mother or father or children or farms, for My sake and for the gospel's sake, but that he shall receive a hundred times as much now in the present age, houses and brothers and sisters and mothers and children and farms, along with persecutions; and in the age to come, eternal life. But many who are first, will be last; and the last, first." (Mark 10:29-31)

As Paul wrote...

What then shall we say to these things? If God is for us, who is against us? (see note Romans 8:31)

The psalmist writes that...

the LORD God is a sun and shield; The LORD gives grace and glory. No good thing does He withhold from those who walk uprightly. O LORD of hosts, How blessed is the man who trusts in Thee! (Psalm 84:11,12) Spurgeon comments on these verses writing

There is no good apart from God, and there is no good which He either needs to keep back or will on any account refuse us, if we are but ready to receive it. We must be upright and neither lean to this or that form of evil; and this uprightness must be practical—we must walk in truth and holiness, then shall we be heirs of all things, and as we come of age all things will be in our actual possession; and meanwhile, according to our capacity for receiving shall be the measure of the divine bestowal. This is true, not of a favored few, but of all the saints forevermore. Verse 12. Here is the key of the psalm. The worship is that of faith, and the blessedness is peculiar to believers. No formal worshiper can enter into this secret. We must know the Lord by the life of real faith, or we can have no true rejoicing in the Lord’s worship, his house, his Son, or his ways.

F W Grant wrote that...

Here the Lord’s words mean plainly, in the connection in which they stand, “Care you for what belongs to God, and suits Him, and He will care for you:” and “His righteousness means all that suits His character, as revealed. Important as the lesson is, it is evidently not what we need to dwell upon in connection with the present inquiry. (Grant, F. W. Leaves From The Book)