Do not give what is holy to dogs, and do not throw your pearls before swine, or they will trample them under their feet, and turn and tear you to pieces (Dogs) (Swine) (Pearls) (ISBE article on Dog) (Mt 7:10:14,15; 15:26; Proverbs 9:7,8; 23:9; 26:11; Acts 13:45-47; Philippians 3:2; Hebrews 6:6; 10:29; 2 Peter 2:22) (Proverbs 11:22) (Mt 22:5,6; 24:10; 2 Corinthians 11:26; 2 Timothy 4:14,15)

Do not give what is holy to dogs - If someone isn’t open to listen to you, there’s no reason to continue speaking.

Solomon writes...

Do not reprove (Hebrew word yakach includes ideas of education, discipline, teaching and admonishing) a scoffer (speaks words showing no respect for the reprover), lest he hate you. Reprove a wise man, and he will love you. (Proverbs 9:8) (Reproof is wasted on a "scoffer" because the more shallow and foolish the person is, the less willing he is to listen to wise, godly counsel)

Jamieson, F, B -

The opposite extreme to that of censoriousness is here condemned—want of discrimination of character.... Religion is brought into contempt, and its professors insulted, when it is forced upon those who cannot value it and will not have it. But while the indiscriminately zealous have need of this caution, let us be on our guard against too readily setting our neighbors down as dogs and swine, and excusing ourselves from endeavoring to do them good on this poor plea.

Spurgeon writes...

There are some holy enjoyments, some gracious experiences, some deep doctrines of the Word of God, which it would be out of place to speak of before certain profane and unclean persons. They would only make a jest of them; perhaps they might persecute you on account of them. No; holy things are for holy men; and as of old the crier in the Grecian temple was wont to say, before the mysteries were performed, “Far hence, ye profane!” so sometimes, before we enter into the innermost circle of Christian converse, it would be well for us to notice who is listening.

***

Zeal should always be tempered by prudence. There are times when it would be treason to truth to introduce it as a topic of conversation,-when men are in such a frame of mind that they will be sure rather to cavil at it than to believe it. Not only speak thou well, but speak thou at the right time, for silence is sometimes golden. See that thou hast thy measure of golden silence as well as of silver speech.

***

When men are evidently unable to perceive the purity of a great truth, do not set it before them. They are like mere dogs, and if you set holy things before them they will be provoked to “turn again and rend you”: holy things are not for the profane. “Without are dogs”: they must not be allowed to enter the holy place. When you are in the midst of the vicious, who are like “swine,” do not bring forth the precious mysteries of the faith, for they will despise them, and “trample them under their feet” in the mire. You are not needlessly to provoke attack upon yourself, or upon the higher truths of the gospel. You are not to judge, but you are not to act without judgment. Count not men to be dogs or swine; but when they avow themselves to be such, or by their conduct act as if they were such, do not put occasions in their way for displaying their evil character. Saints are not to be simpletons; they are not to be judges, but, also, they are not to be fools.

Great King, how much wisdom thy precepts require! I need thee, not only to open my mouth, but also at times to keep it shut.

Give (1325) (didomi) means to give based on decision of will of the giver. Although the tense is not imperative, the force is that of an imperative or command. We are to speak the truth in love, but we are not to allow love to color or distort our sense of discernment.  Note in this warning Jesus is not trying to discourage us from sharing the gospel, but is calling for discernment which is ever looking for listeners with prepared and not antagonistic hearts.

In Hebrews we read that ...

"solid food is for the mature, who because of practice have their senses (Ability to discriminate & make moral decisions. Capacity for spiritual apprehension) trained (gumnazo = having experienced vigorous training and control and in a state of increased moral strength which allows one)  to discern (decide between, make a judgment between) good and evil." (Hebrews 5:14)

This verse makes it clear that Jesus does not exclude every kind of judgment in Matthew 7:1-2 for here He just as plainly commands a certain kind of right judgment or discernment in this verse, for such discrimination is necessary in order to determine who is a dog and a hog! 

Holy (40) (hagios) (Click for an in depth discussion of hagios) refers to that which is is set apart (sanctified) for a special purpose.

Holy and pearls (see discussion below) are somewhat indefinite and as discussed surely include the gospel message but also apply to other holy things besides the gospel, such as the Holy Word, the Holy Spirit, the Holy Name, etc. We are refrain from giving out these holy, precious things out of respect for them more than out of contempt for the opposers. In fact, in this very sermon, Jesus would still call us to "love your enemies, and pray for those who persecute you" (notes Matthew 5:44)

Dogs (2965)  (kuon) in the ancient world does not refer to dogs as we currently think of them for they were seldom household pets but instead were largely half-wild,  dirty, greedy, snarling, vicious, flea-bitten, diseased, mongrel scavenger, that often ran in packs. They are often on the point of starvation and were known to devour corpses, and attack humans, in the night. Clearly literal "dogs" in the ancient word were dangerous and despised. 

Kuon is used 5 times in the NAS and always translated "dog" or "dogs": (Matthew; Luke; Philippians; 2 Peter; Revelation)

For example we read God's prophet Abijah's harsh message to the wife of the evil Jeroboam declaring...

"Anyone belonging to Jeroboam who dies in the city the dogs will eat. And he who dies in the field the birds of the heavens will eat; for the LORD has spoken it." (1 Kings 14:11) (Similar prophecies were decreed against  Baasha’s family, in 1Kings 16:4, and Ahab’s family, 1Kings 21:24.) (For bodies to be devoured by dogs and wild birds of prey was considered one of the worst disgraces that could befall a Jew)

The epithet "dogs" is used figuratively to refer to certain classes of men, expressing their insolent rapacity, Psalms 22:16  and their beastly vices, Deuteronomy 23:18.

It has happened to them according to the true proverb, "A DOG RETURNS TO ITS OWN VOMIT," and, "A sow, after washing, returns to wallowing in the mire." (see notes on 2 Peter 2:22)

Outside are the dogs and the sorcerers and the immoral persons and the murderers and the idolaters, and everyone who loves and practices lying. (Revelation 22:15)

Paul used the term "dogs" in his letter to Philippi warning the converts to...

Beware of the dogs, beware of the evil workers, beware of the false circumcision (see notes Philippians 3:2)

The Jews used "dog" as a derogatory term referring to Gentiles in general. In Philippi, Paul turned the tables so to speak and actually referred to Jews (probably Judaizers) who professed to believe in Christ but depended upon keeping the Law and the rituals of Judaism in order to "merit" salvation. Thus in this sense Paul uses "Dogs" to refer to false teachers.

Barclay has a helpful note on dogs

With us the dog is a well-loved animal, but it was not so in the East in the time of Jesus. The dogs were the pariah dogs, roaming the streets, sometimes in packs, hunting amidst the garbage dumps and snapping and snarling at all whom they met. J. B. Lightfoot speaks of

“the dogs which prowl about eastern cities, without a home and without an owner, feeding on the refuse and filth of the streets, quarrelling among themselves, and attacking the passer-by.”

In the Bible the dog always stands for that than which nothing can be lower. When Saul is seeking to take his life, David’s demand is: “After whom do you pursue? After a dead dog! after a flea!” (1Sa 24:14, cf. 2Ki 8:13; Ps 22:16, 20). In the parable of the Rich Man and Lazarus, part of the torture of Lazarus is that the street dogs annoy him by licking his sores (Luke 16:21). In Deuteronomy the Law brings together the price of a dog and the hire of a whore, and declares that neither must be offered to God (Deut 23:18). In Revelation the word dog stands for those who are so impure that they are debarred from the Holy City (Rev 22:15). That which is holy must never be given to dogs (Mt 7:6). It is the same in Greek thought; the dog stands for everything that is shamelessly unclean. It was by this name that the Jews called the Gentiles. There is a Rabbinic saying, “The nations of the world are like dogs.” So this is Paul’s answer to the Jewish teachers. He says to them, “In your proud self-righteousness, you call other men dogs; but it is you who are dogs, because you shamelessly pervert the gospel of Jesus Christ.” He takes the very name the Jewish teachers would have applied to the impure and to the Gentiles and flings it back at themselves. A man must always have a care that he is not himself guilty of the sins of which he accuses others. (Barclay, W: The Letters to the Philippians, Colossians, and Thessalonians. The New Daily Study Bible Series, Rev. ed. Philadelphia: The Westminster Press. John Knox Press)

Dogs and swine (5519) describe profane people who treat spiritual matters with contempt. They are unbelievers who are enemies of the gospel and are people to avoid.  This verse does not mean that the blessings of the gospel are not to be offered to the Gentiles (remembering that Jews in Jesus' day frequently referred to Gentiles as "dogs"), but rather that precious spiritual truths should not be pressed upon those who are either unready or unwilling to accept or appreciate their value. The verse continues logically in the train of thought developed in the sayings which immediately precede it. While judging others is not the prerogative of man, there are, nonetheless, those whose uncleanness and violence prevent the sharing of the most noble truths of the Christian faith.

"Brothers” (referred to in Mt 7:3-5) and “dogs” or “swine” must not be treated alike. Believers must discriminate carefully, clearly indicating that Jesus' command to stop judging in Matthew 7:1 was not meant to exclude discerning judgment, but only condemnatory, critical judgment.

Swine are just as contemptible and filthy as dogs. The OT mentions swine among the unclean animals (Lev. 11:7; Deut. 14:8) and the eating of swine flesh is an abomination in (Isa. 65:4; 66:3, 17)  Swine are not only unclean animals but can be vicious and are capable of savage attacks against people. The wild boar of the wood was frequently met with in the woody parts of Palestine, especially in Mount Tabor. In Psalm 80:13 the powers that destroyed the Jewish nation are compared to wild boars and wild beasts of the field.

Wild Boars
Can Tear you to Pieces!

The phrase “what is holy” or set apart from the common and profane and consecrated to God is used synonymously with "pearls".

Pearls (3135) (margaritēs) were usually regarded as precious stones in Jesus' day. Pearls are found in the Red Sea, the Persian Gulf, and the Indian Ocean and were brought into the western culture through Alexander the Great’s conquests. Pearls were priced way beyond the purchasing power of the average person and in order to obtain a pearl of great value a merchant might have to sell all his possessions (cf Mt 13:46)

Margaritēs is used by Jesus as a figure of speech for what is of supreme worth.  The Jews used "margaritēs" to refer to a valuable saying. Jesus is saying that whatever is very precious in the spiritual realm should be treated with reverence and not entrusted to those who, because of their utterly wicked, vicious, and despicable nature, are like dogs and hogs.

Trample (2662 (katapateo from katá = intensifies meaning + patéo = tread, trample, fig to treat contemptuously) means to step down forcibly upon often with the implication of seeking to destroy or ruin. The idea is to spurn, to reject with disdain, treat contemptuously, treat with rudeness and insult or thoroughly despise someone or something. Jesus pictures hogs trampling the pearls with their feet, thus treating them with utter disdain.

In Matthew Jesus returns to Nazareth, His home town, and we read that

they took offense (verb skandalizo - see in depth study of noun, skandalon) at Him. But Jesus said to them, "A prophet is not without honor except in his home town, and in his own household." And He did not do many miracles there because of their unbelief. (Mt 13:57-58)

So here we see Jesus practicing the same principle He is laying down for His disciples to practice.

D A Carson comments that...

The pigs trample the pearls under foot (perhaps out of animal disappointment that they are not morsels of food), and the dogs are so disgusted with "what is sacred" that they turn on the giver. Gaebelein, F, Editor: Expositor's Bible Commentary 6-Volume New Testament. Zondervan Publishing)

Spurgeon comments that...

It is a pity to talk about some of the secrete of our holy faith in any and every company. It would be almost, profane to speak of them in the company of profane men. We know that they would not. understand us; they would find occasion for jest and ridicule, and therefore our own reverence for holy things must cause us to lay a finger on our lips when we are in the presence of profane persons. Do not let us, however, carry out one precept to the exclusion of others. There are dogs that eat of the crumbs that fall from the master’s table. Drop them a crumb. And there are even swine that may yet be trans. learned; to whom the sight of a pearl might give some inkling of a better condition of heart. Cast not the pearls before them, but you may show them to them sometimes when they are in as good a state of mind as they are likely to be in. It is ours to preach the gospel to every creature; that is a precept of Christ, and yet all creatures are not always in the condition to hear the gospel. We must choose our time. Yet even this I would not push too far. We are to preach the gospel in season and out of season. Oh! that we may be able to follow precepts as far as they are meant to go, and no further.

Turn (4762) ( strepho from trope = a turn or revolution) means to twist, turn quite around or reverse.

Tear (4486) (rhegnumi) means to break in pieces, disrupt or lacerate as dogs would do.

Clearly to be an undiscerning simpleton (as might occur in one who took the meaning of "do not judge" to an extreme interpretation which Jesus did not intend) can place one in a dangerous position (cf "trample", "tear to pieces"!)

Paul gives us an example of a vicious opponent of the gospel warning Timothy to beware of...

Alexander the coppersmith did me much harm; the Lord will repay him according to his deeds. Be on guard against him yourself, for he vigorously opposed our teaching. (notes 2 Timothy 4:14-15)

The French philosopher Voltaire would certainly fit the picture of a spiritual "dog and a hog", who violently opposed God, His Holy Word and His precious Son. How tragic that one of the most fertile and talented minds of his time (which parenthetically bears witness to the common grace and longsuffering of our great Father), was such a vicious opponent of truth, using his pen to retard and demolish Christianity as much as humanly possible. Once speaking about our Lord Jesus Christ, Voltaire uttered the unspeakable words "Curse the wretch!" Voltaire was so self deceived and arrogant that he once boasted that within

"twenty years Christianity will be no more. My single hand shall destroy the edifice it took twelve apostles to rear."

God however is not mocked beloved (see Galatians ) and so not surprisingly shortly after Voltaire's death the very house in which he printed his vicious anti-Christian literature became the home of the Geneva Bible Society! A nurse who attended Voltaire at the time of his horrible death vowed "For all the wealth in Europe I would not see another infidel die." Voltaire's' physician, Trochim, also attended the infidel up to the time of his last breath, and is quoted as hearing Voltaire's last desperate (rightly so) cry

"I am abandoned by God and man! I will give you half of what I am worth if you will give me six months' life. Then I shall go to hell; and you will go with me. O Christ! O Jesus Christ!"

Voltaire is the epitome of the type of individual citizens of the Kingdom of Heaven must refrain from sharing the precious and holy truths of God.

We are not to continue to present the gospel to those who repeatedly mock, scorn and deride it. To be sure, this determination sometimes is obvious as in the case of rank infidels but in other situations requires God's wisdom (see role of prayer in Matthew 7:7-8) and Spirit controlled guidance. There is a limit Jesus says and when that time arrives, it is high time for the ambassador of Christ to depart company.

And so we see Jesus instructing His disciples...

"And into whatever city or village you enter, inquire who is worthy in it; and abide there until you go away. And as you enter the house, give it your greeting. And if the house is worthy, let your greeting of peace come upon it; but if it is not worthy, let your greeting of peace return to you. And whoever does not receive you, nor heed your words, as you go out of that house or that city, shake off the dust of your feet. Truly I say to you, it will be more tolerable for the land of Sodom and Gomorrah in the day of judgment, than for that city." (Matthew 10:11-15)

In the same way Jesus pronounced judgment on the Galilean towns which for the most part rejected the light of His presence and His gospel..

Woe to you, Chorazin! Woe to you, Bethsaida! For if the miracles had occurred in Tyre and Sidon which occurred in you, they would have repented long ago in sackcloth and ashes. Nevertheless I say to you, it shall be more tolerable for Tyre and Sidon in the day of judgment, than for you. And you, Capernaum, will not be exalted to heaven, will you? You shall descend to Hades; for if the miracles had occurred in Sodom which occurred in you, it would have remained to this day. (Mt 11:21-23)

And we see Paul's reaction to the rejection of the Gospel by the Jews of Corinth...

After these things he left Athens and went to Corinth. And he found a certain Jew named Aquila, a native of Pontus, having recently come from Italy with his wife Priscilla, because Claudius had commanded all the Jews to leave Rome. He came to them, and because he was of the same trade, he stayed with them and they were working; for by trade they were tent-makers. And he was reasoning in the synagogue every Sabbath and trying to persuade Jews and Greeks. But when Silas and Timothy came down from Macedonia, Paul began devoting himself completely to the word, solemnly testifying to the Jews that Jesus was the Christ. And when they resisted and blasphemed, he shook out his garments and said to them, "Your blood be upon your own heads! I am clean. From now on I shall go to the Gentiles. (Acts 18:1-6, see also Acts 13:44-51, 28:17-28; Ro 16:17-18).

Writing to Titus on the Isle of Crete Paul instructed him...

Reject a factious (divisive, one who causes division) man after a first and second warning, knowing that such a man is perverted and is sinning, being self-condemned. (Titus 3:10-11)

Herod Antipas was a dog...swine, who heard John gladly, Mark recording...

for Herod was afraid of John, knowing that he was a righteous and holy man, and kept him safe. And when he heard him, he was very perplexed; but he used to enjoy listening to him. Mark 6:20)

This same Herod turned on John the Baptist and had him beheaded him (see Mt 14:1-12; Mk 6:14-28; Lu 9:7-9). Later, Jesus Christ refused to give what was holy to Herod...

Now Herod was very glad when he saw Jesus; for he had wanted to see Him for a long time, because he had been hearing about Him and was hoping to see some sign performed by Him. And he questioned Him at some length; but He answered him nothing. (Luke 23:8-9)

And after Jesus rose from the dead He showed Himself to no one who was not a believer.

In the parable of The Barren Fig Tree Jesus explained that God was patience, but His patience was not endless...

And He began telling this parable: "A certain man had a fig tree which had been planted in his vineyard; and he came looking for fruit on it, and did not find any. And he said to the vineyard-keeper, 'Behold, for three years I have come looking for fruit on this fig tree without finding any. Cut it down! Why does it even use up the ground?' And he answered and said to him, 'Let it alone, sir, for this year too, until I dig around it and put in fertilizer; and if it bears fruit next year, fine; but if not, cut it down.'" (Luke 13:6-9)

Solomon presents a similar principle regarding bestowal of "holy things" on dogs and hogs...

A man who hardens his neck after much reproof will suddenly be broken beyond remedy. (Proverbs 29:1)

Do not reprove a scoffer, lest he hate you (don't bother rebuking mockers; they will only hate you), Reprove a wise man, and he will love you. (Proverbs 9:8)

Jesus' teaching is in fact imminently logical for if we were to remain in the company of those who constantly ridicule the small gate and narrow way of the Gospel, we would by default, fail to enter other "fields" which Jesus described in other passages declaring...

The harvest is plentiful, but the workers are few. (Mt 9:37)

Behold, I say to you, lift up your eyes, and look on the fields, that they are white for harvest. (John 4:35)

Hendriksen writes that...

The suggestion may be correct that, since pearls resemble peas or acorns, these hogs, having greedily tasted a few and having discovered that they can do nothing with them, in anger trample the pearls underfoot and turn and tear to pieces those who had flung such non-edibles in front of them. (Hendriksen, W., & Kistemaker, S. J. Exposition of the Gospel According to Matthew Grand Rapids: Baker Book House)

J Vernon McGee tells the following story...