What does Matthew 5:33-37 mean?

³³ Again, ye have heard that it hath been said by them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths: ³⁴ But I say unto you, Swear not at all; neither by heaven; for it is God’s throne: ³⁵ Nor by the earth; for it is his footstool: neither by Jerusalem; for it is the city of the great King. ³⁶ Neither shalt thou swear by thy head, because thou canst not make one hair white or black. ³⁷ But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.  (Matthew 5:33-37 KJV)

Oaths and swearing

We have here an exposition of the third commandment, which we should rightly understand, because it is specifically stated that God will not hold guiltless anyone who takes His name in vain, even if the person excuses himself. Now, as to this command:

It is universally agreed that it forbids perjury, false swearing, and breaking oaths and vows (Matthew 5:33). This was taught to those of old, and it is the true intent and meaning of the third commandment: You shall not use or take the name of God—in an oath—in vain, or to support a lie. “He has not lifted up his soul to vanity” is explained in the next words: “nor sworn deceitfully” (Psalm 24:4). Perjury is condemned by the light of nature, as it shows both irreverence toward God and injustice toward man, and it exposes a person to divine wrath. This was always believed to follow perjury so certainly that common forms of swearing became imprecations, such as, “God do so to me, and more also,” and in our time, “So help me God,” implying that if one swears falsely, he hopes never to receive help from God. Across nations, men have cursed themselves in this way, not doubting that God would curse them if they lied under oath.

It is also said, from other Scriptures, “but shall perform to the Lord your oaths” (Numbers 30:2), which may refer to either:

1. Promises in which God is directly involved—vows made to God—which must be carefully fulfilled (Ecclesiastes 5:4-5), or,
2. Promises made to others, with God as witness, because He is appealed to for our sincerity. These promises must be fulfilled with reverence for God, to whom we become indebted when we confirm our words with an oath. If we break such a promise, we have not only lied to men, but to God.

The commandment also forbids rash and unnecessary swearing: “Do not swear at all” (Matthew 5:34; compare James 5:12). This does not mean all swearing is sinful. When properly done, it is a form of religious worship that gives God the glory due His name (see Deuteronomy 6:13; 10:20; Isaiah 45:23; Jeremiah 4:2). Paul sometimes confirmed what he said with solemn oaths (2 Corinthians 1:23), when necessary. In swearing, we use the certainty of what is known to confirm what is uncertain. We appeal to a higher knowledge and a righteous Judge, calling down judgment if we swear falsely.

Christ’s mind in this matter is:

1. We must not swear at all unless we are rightly called to it, when justice, love for our neighbor, or public interest makes it necessary for ending disputes (Hebrews 6:16). The civil magistrate usually judges that necessity. We may be sworn, but we must not swear unnecessarily. We may be legally required to swear, but must not do it for personal gain.
2. We must not swear lightly or irreverently in everyday speech. It is a serious sin to make a casual appeal to the glorious Majesty of heaven. God’s name is sacred and should only be used with the utmost seriousness. Casual swearing is a gross misuse of God’s holy name and a sign of a heart that lacks grace and reverence. “Your enemies take Your name in vain.”
3. We must especially avoid promissory oaths—those that bind us to future actions. These are the oaths Christ refers to particularly. Once we’ve truthfully testified under an affirmative oath, our obligation ends. But a promissory oath binds us for the future and may be broken by temptation or unexpected circumstances. It should not be taken without serious necessity. Frequent use of oaths reflects poorly on Christians, whose honesty should be so trustworthy that their words are as reliable as their oaths.
4. We must not swear by any created thing. Some people avoided using God’s name directly and instead swore by heaven or earth, etc. Christ forbids this (Matthew 5:34) and shows that everything we might swear by is in some way connected to God, the source of all being. It is just as serious to swear by these as to swear by God Himself.

(1) Don’t swear by heaven: “As sure as there is a heaven, this is true.” But heaven is God’s throne (Isaiah 66:1), the place where He reveals His glory, so swearing by heaven is swearing by God.

(2) Don’t swear by the earth, for it is His footstool. God governs the earth as He does heaven. Though under His feet, it is still under His care and ownership (Psalm 24:1). Swearing by the earth is swearing by its Owner.

(3) Don’t swear by Jerusalem. The Jews deeply revered it, and some thought swearing by it was sacred. But Jerusalem is the city of the great King (Psalm 48:2), the city of God (Psalm 46:4), and so swearing by it involves God.

(4) Don’t swear by your head. Though it is part of you, it belongs more to God than to you. He created it and formed its faculties, and you can’t even change the color of one hair on it by your own power. So to swear by your head is to swear by the One who gives it life (Psalm 3:3).

5. Therefore, in all our speech, we should be content with “Yes, yes” and “No, no” (Matthew 5:37). In ordinary conversation, affirm something by saying, “Yes, it is so,” or if necessary for emphasis, repeat it: “Yes, yes, indeed it is so.” Our Savior used “Truly, truly,” as His “yes, yes.” Likewise, if we deny something, it should be enough to say, “No,” or repeat it if needed. If our integrity is known, that should be sufficient. If it’s questioned, swearing only increases suspicion. Those who can use a profane oath easily are unlikely to hesitate at lying. It’s unfortunate that what Christ taught His disciples—plain, honest speech—has been mocked or labeled as sectarian, when we are not only forbidden to use more than yes and no, but practically directed to speak that way.

The reason is noteworthy: “Whatever is more than these comes from evil,” even if it doesn’t rise to the level of an oath. One ancient copy even says it “comes from the evil one”—the Devil. It stems from human corruption, passion, vanity, and irreverence. It comes from deceit and distrust; people rely on oaths because they don’t trust each other to speak the truth. “All men are liars.” So, people use extra assurances because honesty is doubted. Christians should, for the sake of their faith, avoid not only things that are inherently evil, but also those that arise from evil or have the appearance of it. If something springs from a bad cause, it should be avoided. An oath is like medicine—it assumes there’s a sickness.