Albert Barnes Commentary Matthew 5:37

"But let your speech be, Yea, yea; Nay, nay: and whatsoever is more than these is of the evil [one]." — Matthew 5:37 (ASV)

Your communication. Your word; what you say.

Be, Yea. Yes. This does not mean that we should always use the word yea, for it might as well have been translated yes. But it means that we should simply affirm, or declare that a thing is so.

More than these. More than these affirmations. Profane oaths come from evil.

Comes from evil. Is evil. It proceeds from some evil disposition or purpose. And from this we may learn:

1. That profane swearing is always the evidence of a depraved heart. To trifle with the name of God, or with any of his works, is itself most decided proof of depravity.
2. That no man is believed any sooner in common conversation because he swears to a thing. When we hear a man swear to a thing, it is pretty good evidence that he knows what he is saying to be false, and we should be on our guard. He who will break the third commandment will not hesitate to break the ninth also. This explains the fact that profane swearers are seldom believed. The man who is always believed is he whose character is beyond suspicion in all things; who obeys all the laws of God; and whose simple declaration therefore is enough. A man who is truly a Christian and leads a Christian life does not need oaths and profaneness to be believed.
3. It is no mark of a gentleman to swear. The most worthless and vile, the refuse of mankind, the drunkard and the prostitute, swear as well as the best-dressed and educated gentleman. No particular endowments are requisite to give a finish to the art of cursing. The basest and meanest of mankind swear with as much tact and skill as the most refined; and he who wishes to degrade himself to the very lowest level of pollution and shame should learn to be a common swearer. Any man has talents enough to learn to curse God and his fellow men, and to pray—for every man who swears, prays—that God would sink him and others into hell. No profane man can be sure that God will not hear his prayer and send him to the regions of woe.
4. Profaneness does no man any good. No man is the richer, or wiser, or happier for it. It helps no one's education or manners. It commends no one to any society. The profane man must be, of course, shut out from female society; and no refined intercourse can consist with it. It is disgusting to the refined; abominable to the good; insulting to those with whom we associate; degrading to the mind; unprofitable, needless, and injurious in society; and awful in the sight of God.
5. God will not hold the profane swearer guiltless. Wantonly to profane his name; to call his vengeance down; to curse him on his throne; to invoke damnation, is perhaps of all offences the most awful. And there is not in the universe more cause of amazement at his forbearance than that God does not rise in vengeance and smite the profane swearer at once to hell. Truly, in a world like this, where his name is profaned every day, and hour, and moment by thousands, God shows that he is slow to anger and that his mercy is without bounds!