Church Fathers Commentary Matthew 5:33-37

"Again, ye have heard that it was said to them of old time, Thou shalt not forswear thyself, but shalt perform unto the Lord thine oaths: but I say unto you, swear not at all; neither by the heaven, for it is the throne of God; nor by the earth, for it is the footstool of his feet; nor by Jerusalem, for it is the city of the great King. Neither shalt thou swear by thy head, for thou canst not make one hair white or black. But let your speech be, Yea, yea; Nay, nay: and whatsoever is more than these is of the evil [one]." — Matthew 5:33-37 (ASV)

Glossa Ordinaria: The Lord has until now taught to abstain from injuring our neighbor, forbidding anger with murder, lust with adultery, and the putting away of a wife with a bill of divorce. He now proceeds to teach abstaining from injury to God, forbidding not only perjury as an evil in itself, but even all oaths as the cause of evil, saying, Ye have heard that it was said by them of old, Thou shalt not forswear thyself.¹

It is written in Leviticus, Thou shalt not forswear thyself in my name (Leviticus 19:12). And so that they would not make gods of the creature, they are commanded to render their oaths to God, and not to swear by any creature: Render to the Lord thy oaths. That is, if you have occasion to swear, you shall swear by the Creator and not by the creature, as it is written in Deuteronomy, Thou shalt fear the Lord thy God, and shalt swear by his name (Deuteronomy 6:13).

St. Jerome: This was allowed under the Law, as if to children. Just as they offered sacrifice to God so that they would not offer it to idols, so they were permitted to swear by God—not that the act was right, but that it was better done to God than to demons.

Pseudo-Chrysostom: For no one can swear often without sometimes swearing falsely, just as one who has a habit of speaking a lot will sometimes speak foolishly.

St. Augustine of Hippo: Since the sin of perjury is a grave sin, the one who uses no oath is further removed from it than the one who is ready to swear on every occasion. The Lord would rather that we not swear and so stay close to the truth, than that by swearing we should come near to perjury.²

This precept also confirms the righteousness of the Pharisees—that is, not to swear falsely—since one who does not swear at all cannot swear falsely. But since calling God to witness is to swear, does the Apostle not break this commandment when he says to the Galatians, The things which I write unto you, behold, before God, I lie not (Galatians 1:20)? And to the Romans, God is my witness, whom I serve in my spirit (Romans 1:9)?³

Perhaps someone might say that it is not an oath unless one uses the form of swearing by some object, and that the Apostle did not swear when he said, "God is my witness." It is ridiculous to make such a distinction. Yet the Apostle has used even this form: I protest by your rejoicing which I have in Christ Jesus our Lord, I die daily (1 Corinthians 15:31). That this is an oath, and does not mean "your boasting has caused me to die daily," is clear from the Greek.

But what we cannot understand by words alone, we may gather from the conduct of the saints. Their example helps us understand a teaching that might otherwise be easily misinterpreted. The Apostle used oaths in his Epistles, and by this he shows us how we should understand the command, I say unto you, Swear not at all.

Specifically, it is a warning: lest by allowing ourselves to swear at all we become ready to swear, from readiness we develop a habit of swearing, and from a habit we fall into perjury. And so, the Apostle is found to have used an oath only in writing, where the greater thought and caution required does not allow for a slip of the tongue.⁴

Yet the Lord's command, Swear not at all, is so universal that He would seem to have forbidden it even in writing. But since it would be impious to accuse Paul of violating this precept, especially in his Epistles, we must understand the phrase "at all" to mean that, as far as it is in your power, you should not make a practice of swearing or seek it as a good thing in which to take delight.

Therefore, the Apostle is found to have used an oath in several places in his writings, since writing allows for greater caution. He did this so that no one might suppose there is any direct sin in swearing to what is true, but only that our weak hearts are better preserved from perjury by abstaining from all swearing whatsoever.⁵

St. Jerome: Finally, consider that the Savior here does not forbid swearing by God, but by heaven, the earth, Jerusalem, or by a man's head. The Jews always had this evil practice of swearing by the elements, and for this they are often accused in the prophetic writings. For one who swears shows either reverence or love for that by which he swears. Thus, when the Jews swore by the angels, by the city of Jerusalem, by the temple, and by the elements, they paid to the creature the honor and worship belonging to God. For it is commanded in the Law that we should swear only by the Lord our God.

St. Augustine of Hippo: Alternatively, the text adds, neither by heaven... nor by the earth, because the Jews did not consider themselves bound when they swore by such things. It is as if Christ said, "When you swear by heaven and earth, do not think that you do not owe your oath to the Lord your God, for you are proven to have sworn by Him whose throne is heaven and whose footstool is the earth."

This is not meant as though God has limbs set upon heaven and earth like a man who is sitting. Rather, that throne signifies God's judgment over us. And since, in the whole universe, heaven has the highest beauty, God is said to sit on the heavens to show that divine power is more excellent than the most surpassing beauty. He is said to stand on the earth, as putting a lesser beauty to its lowest use.⁶

Spiritually, "heaven" denotes holy souls and "earth" denotes the sinful, seeing that he that is spiritual judgeth all things (1 Corinthians 2:15). But to the sinner it is said, Earth thou art, and unto earth shalt thou return (Genesis 3:19). And one who would live under a law is put under a law; therefore, He adds, it is his footstool. Neither by Jerusalem, for it is the city of the great King. This is better said than "it is mine," though it is understood to mean the same. And because He is also truly Lord, whoever swears by Jerusalem owes his oath to the Lord.

Neither shalt thou swear by thy head. What could anyone think is more entirely his own property than his own head? But how is it ours when we do not have the power to make one hair black or white? Therefore, whoever swears by his own head also owes his vows to the Lord. By this example, the rest may be understood.

St. John Chrysostom: Note how He exalts the elements of the world, not because of their own nature, but because of their relation to God, so that no occasion for idolatry is opened.

Rabanus Maurus: Having forbidden swearing, He instructs us how we ought to speak: Let your communication be, Yea, yea; Nay, nay. That is, to affirm anything, it is sufficient to say, "It is so"; to deny, to say, "It is not so."

Or, "yes, yes; no, no," is repeated so that what you affirm with your mouth, you should prove in deed, and what you deny in word, you should not establish by your conduct.

St. Hilary of Poitiers: Alternatively, those who live in the simplicity of the faith do not need to swear. For them, what is, is, and what is not, is not. By this, their life and their speech are always preserved in truth.

St. Jerome: Therefore, evangelical truth does not admit an oath, since the entire discourse of the faithful serves in place of an oath.

St. Augustine of Hippo: One who has learned that an oath is to be reckoned not among good things, but among necessary things, will restrain himself as much as he can from using an oath without necessity. He will use one only when he sees that people are reluctant to believe something that is for their own good without the confirmation of an oath.

This, then, is good and to be desired: that our speech be only, "Yes, yes; No, no." For whatsoever is more than these cometh of evil. That is, if you are compelled to swear, you know that it is because of the weakness of those you are trying to persuade, and this weakness is surely an evil. What is "more than this" is evil in this sense: not that you do evil in making just use of an oath to persuade another of something beneficial, but the evil is in the person whose weakness obliges you to use an oath.

St. John Chrysostom: Alternatively, "of evil" means from the weakness of those to whom the Law permitted the use of an oath. This does not mean that the old Law is from the Devil, but that Christ leads us from the old imperfection to the new abundance.

1. non occ.
2. cont. Faust., xix. 23
3. Serm. in Mont., i, 17
4. de Mendac. 15
5. cont. Faust., xix, 23
6. Serm. in Mont., i, 17