Matthew 5:34–36

So the Lord goes far beyond perjury or breaking a vow. He forbids swearing altogether in the dealings of daily life. Our word there is to be, Yes, yes, or No, no... The Lord draws His examples from Jewish habit. All such strong assertion grew out of men's constant experience of deceiving and evading. So they used these means to guarantee the truth. But these efforts defeated themselves. We know from a reliable Jewish writer of New Testament times that no one counted oaths by earth, heaven, sun, stars, or the whole universe as binding. Only an oath that named God outright bound the conscience. Men might even break the rest.

It was wrong to think a man could freely use these substitute phrases, as long as he did not mention the name of God. Heaven is God's throne, the earth is God's footstool (Isa. 66:1) and Jerusalem is the city of God and of His King (Psa. 48:1-2). A man who swore by his head was offering his own life as security for the oath. He should remember well that God alone is Lord over life and death. He does not even have the power to change the colour of one hair of his head.

Man cannot even change the colour of a hair. That shows his utter weakness fully and simply, and it forms (at least in part) the basis of the prohibition. God might swear, for He could carry it out, and He knew all the consequences of what He pledged Himself to. We see Him do this beautifully when He wants to reassure His creature, who is so quick to doubt even the perfect faithfulness of his God.

It is quite enough that in our dealings with fellow believers or with other people, our yes should be yes and our no, no. "Anything more than this comes from evil." The believer is as responsible to speak as to act as in the presence of God. This is his regular privilege and safeguard... The evil one is a liar and the father of lies. He would gain a real opening if the Christian were not always watchful to speak truly, and needed such extra words before people believed him.

The same principle that stops me swearing on my own account makes me take what is called an oath before a magistrate. In the one case I bring God in lightly; in the other I acknowledge Him in the magistrate, as I am bound to do. The Lord and James speak only of voluntary oaths — what comes from self... When a magistrate imposes an oath, he is putting me under oath by his authority. I judge a man to be wholly at fault if he refuses that oath. He disowns God's authority in the magistrate.

Notice how our Lord acted before the high priest. It is practical proof of the distinction drawn here. He was silent until the high priest put the oath to Him; then at once He answers. Who can doubt that He shows us the right pattern there?

Deuteronomy 23:21-23 plainly warned Israel that a vow, once made, was binding. They did not have to make such oaths, but if they did, no excuse could cover a failure to keep one. The Lord Jesus, though, forbids the making of oaths. To swear an oath was to promise to do something in the future. People often used God's name in these oaths (1 Sam. 30:15; 1 Kings 17:1). But holding back from God's name led them to swear by heaven, earth, Jerusalem, and even their own head. And that in turn led to empty oaths, made with no intention of keeping them.

It was a wrong idea to think one could freely use these substitute phrases, as long as one did not mention the name of God. Heaven is God's throne, the earth is God's footstool (Isa. 66:1) and Jerusalem is the city of God and of His King (Psa. 48:1-2).

Men also think little of swearing by heaven. Many use the word "heavens" as an exclamation. But heaven is God's throne, so such swearing means swearing by Him who sits on the throne. All of this shows how little people recognise the supreme honour that belongs to God.

Men were forever deceiving or evading each other. All the strong oaths the Lord points to in Jewish habit grew out of that. People turned to them as a way of guaranteeing the truth. But these efforts defeated themselves. A reliable Jewish writer from the time of the New Testament tells us that oaths by earth, heaven, sun, stars and the whole universe were not counted binding. Only an oath that named God directly bound the conscience; the rest could be broken. The Lord assumed poverty of spirit and purity of heart in those He addressed. So He forbade all such swearing. It offends God, and it does not fit the place of His sons.

Significant here is the description of Jerusalem as the city of the great King. This will be during the millennial reign. When the kingdom has come, praise will be heard in the heavens, in the earth and in Jerusalem. Now the earth is full of swearing and wicked words. But in that coming day the offences will be gathered out of the kingdom.

To Jerusalem alone belongs this title, and it is no empty distinction. The great King Himself, the Judge of Israel, was struck on the cheek there and nailed to the cross. Scripture had to be fulfilled that way. For its sin that same city became a byword and a curse among the nations. Yet it is to be known as the joy of the whole earth, because the same Messiah will be present there in majesty. His glory was once turned to shame, when men wrote over the head of the crucified Son of God, in cruel and mocking scorn, "Jesus of Nazareth, the King of the Jews."

Many of the old church fathers — Justin, Irenaeus, Origen and Jerome — understood the Lord's words, "swear not at all," to mean that a Christian should never take an oath. Groups such as the Quakers and Jehovah's Witnesses also refuse every kind of oath.

The question here (as in James) is not in the least a judicial oath. The Lord is dealing with how His disciples behave as individuals, not with their relation to the governing powers. Heaven, earth, Jerusalem and a man's own head were ways of swearing in everyday Jewish talk. They were not the oaths used when God's authority is called in to draw out the truth about facts. That is why the Lord Himself, though silent before, answered when the high priest put Him under oath by the living God (Matt. 26:62-64).

It was a mistake to think one could freely use these substitute phrases, as long as one did not mention the name of God. Heaven is God's throne, the earth is God's footstool (Isa. 66:1) and Jerusalem is the city of God and of His King (Psa. 48:1-2). A man who swore by his head wanted to put down his own life as security for his oath. He ought to remember that God alone is Lord over life and death. He himself does not even have the power to change the colour of one hair of his head.

The Lord goes far beyond perjury or breaking a vow. He forbids swearing altogether in the ordinary dealings of daily life. Our word in them is to be Yes, yes, or No, no. Anything more than these has no sanction from God, and is therefore of evil, or of the evil one, the enemy of God and man. The Lord draws His examples from Jewish habit. All such strong affirmations arose because men were forever deceiving or evading. So they resorted to such means of guaranteeing the truth. But these efforts defeated themselves. A reliable Jewish writer from New Testament times tells us that people did not treat oaths by earth, heaven, sun, stars, or the whole universe as binding. Only oaths that named God in plain, direct words bound the conscience. The rest they might even break.

The Lord sweeps into His prohibition all these evasions of the third commandment, putting them into the same category with what was once permitted. Man's utter weakness is shown fully and simply by his inability even to change the colour of a hair. That weakness is, at least in part, the basis of the prohibition. God might swear, for He could carry it out, and He knew all the consequences of what He pledged Himself to. It is beautiful to see Him do it. He does it to assure the soul of His creature, who is so ready to doubt the perfect faithfulness even of his God.

Faith, on the contrary, raises the soul above the difficulty, straight to God Himself, and enables one to "stand still." We gain nothing by our restless and anxious efforts. "We cannot make one hair white or black," nor "add one cubit to our stature."

Christianity has no place for oaths, whether sworn seriously or in vain. Israel's law had proved that man in the flesh cannot be trusted. They had vowed to keep the law, and they broke it again and again. So we must not dare to stress how dependable our own word is. Instead we should depend completely on the truth of the word of God. This is the effect of grace.

Here the reference is not a judicial oath, that is, an oath administered by a magistrate… The matter here relates to communication between man and man. … Suppose our Lord had meant to forbid the Christian from taking judicial oaths. Would He not have used as His example the oath that was usual in the courts of those days? … If the magistrate does not acknowledge God in the oath, the Christian is still bound to acknowledge God in the magistrate, who is a servant of God in the outward things of this world.

In our dealings with fellow believers or with anyone else, it is quite enough that our yes should be yes, and our no, no. … The believer is as responsible to speak as to act in the presence of God. This is his constant privilege and safeguard… The evil one is a liar and the father of it. Suppose the Christian were not always watchful to speak truly, and needed extra words before people would believe him. That would give him no small opportunity.