Matthew 5:34

Next, to lead them farther away from swearing by God, He saith, "Neither by Heaven, for it is God's throne, nor by the earth, for it is the footstool of His feet; nor by Jerusalem, for it is the city of the great King:" still speaking out of the prophetical writings, and signifying Himself not to be opposed to the ancients. This was because they had a custom of swearing by these objects, and He intimates this custom near the end of His Gospel. But mark, I pray thee, on what ground He magnifies the elements; not from their own nature, but from God's relation to them, such as it had been in condescension declared. For because the tyranny of idolatry was great, that the elements might not be thought worthy of honor for their own sake, He hath assigned this cause, which we have mentioned, which again would pass on to the glory of God. For He neither said, "because Heaven is beautiful and great," nor, "because earth is profitable;" but "because the one is God's throne, the other His footstool;" on every side urging them on towards their Lord.

Lastly, consider that the Saviour does not here forbid to swear by God, but by the Heaven, the Earth, by Jerusalem, by a man's head. For this evil practice of swearing by the elements the Jews had always, and are thereof often accused in the prophetic writing's. For he 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 the elements, they paid to the creature the honour and worship belonging to God; for it is commanded in the Law that we should not swear but by the Lord our God.

(de Mendac. 15.) But what we could not understand by mere words, from the conduct of the saints we may gather in what sense should be understood what might easily be drawn the contrary way, unless explained by example. The Apostle has used oaths in his Epistles, and by this shows us how that ought to be taken, I say unto you, Swear not at all, namely, lest by allowing ourselves to swear at all we come to readiness in swearing, from readiness we come to a habit of swearing, and from a habit of swearing we fall into perjury. And so the Apostle is not found to have used an oath but only in writing, the greater thought and caution which that requires not allowing of slip of the tongue. Yet is the Lord's command so universal, Swear not at all, that He would seem to have forbidden it even in writing. But since it would be an impiety to accuse Paul of having violated this precept, especially in his Epistles, we must understand the word at all as implying that, as far as lays in your power, you should not make a practice of swearing, not aim at it as a good thing in which you should take delight. (cont. Faust. xix. 23.) Therefore in his writings, as writing allows of greater circumspection, the Apostle is found to have used an oath in several places, that none might suppose that there is any direct sin in swearing what is true; but only that our weak hearts are better preserved from perjury by abstaining from all swearing whatever. (Serm. in Mont. i. 17.) Or; It is added, By the Heaven, &c. because the Jews did not consider themselves bound when they swore by such things. As if He had said, When you swear by the Heaven and the Earth, think not that you do not owe your oath to the Lord your God, for you are proved to have sworn by Him whose throne the heaven is, and the earth His footstool; which is not meant as though God had such limbs set upon the heaven and the earth, after the manner of a man who is sitting; but that seat signifies God's judgment of us. And since in the whole extent of this universe it is the heaven that has the highest beauty, God is said to sit upon the heavens as showing divine power to be more excellent than the most surpassing show of beauty; and He is said to stand upon the earth, as putting to lowest use a lesser beauty. Spiritually by the heavens are denoted holy souls, by the earth the sinful, seeing He that is spiritual judgeth all things. (1 Cor. 2:15.) But to the sinner it is said, Earth thou art, and unto earth thou shalt return. (Gen. 3:19.) And he who would abide under a law, is put under a law, and therefore He adds, it is the footstool of His feet. 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, whoso swears by Jerusalem, owes his oath to the Lord. Neither by thy head. What could any think more entirely his own property than his own head? But how is it ours when we have not power to make one hair black or white? Whoso then swears by his own head also owes his vows to the Lord; and by this the rest may be understood.

For no man can swear often, but he must sometimes forswear himself; as he who has a custom of much speaking will sometimes speak foolishly.

"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." Why did He go straightway not to theft, but to false witness, passing over that commandment? Because he that steals, doth upon occasion swear also; but he that knows not either swearing or speaking falsehood, much less will he choose to steal. So that by this He hath overthrown the other sin likewise: since falsehood comes of stealing. But what means, "Thou shalt perform unto the Lord thine oaths?" It is this, "thou shalt be true in swearing." "But I say unto you, swear not at all." Next, to lead them farther away from swearing by God, He saith, "Neither by Heaven, for it is God's throne, nor by the earth, for it is the footstool of His feet; nor by Jerusalem, for it is the city of the great King:" still speaking out of the prophetical writings, and signifying Himself not to be opposed to the ancients. This was because they had a custom of swearing by these objects, and he intimates this custom near the end of his Gospel. But mark, I pray thee, on what ground He magnifies the elements; not from their own nature, but from God's relation to them, such as it had been in condescension declared. For because the tyranny of idolatry was great, that the elements might not be thought worthy of honor for their own sake, He hath assigned this cause, which we have mentioned, which again would pass on to the glory of God. For He neither said, "because Heaven is beautiful and great," nor, "because earth is profitable;" but "because the one is God's throne, the other His footstool;" on every side urging them on towards their Lord.