Let us then also imitate Him. Let us cast out that spirit of murder and enmity. It is not enough not to retaliate (for even in the Old Dispensation this was exemplified); but let us do all as we would for bosom-friends, as we would for ourselves so for those who have injured us. We are followers of Him, we are His disciples, who after being crucified, sets everything in action in behalf of his murderers, and sends out His Apostles to this end. And yet we have often suffered justly; but those acted not only unjustly, but impiously; for He was their Benefactor, He had done no evil, and they crucified Him. And for what reason? For the sake of their reputation. But He Himself made them objects of reverence. “The scribes and the pharisees sit in Moses' seat; all therefore whatsoever they bid you observe, that do ye, but after their works do ye not.” And again in another place, “Go your way, show yourself to the priest.” Besides, when He might have destroyed them, He saves them. Let us then imitate Him, and let no one be an enemy, no one a foe, except to the devil.
Not a little does the habit of not swearing contribute to this end: I mean to the not giving way to wrath: and by not giving way to wrath, we shall not have an enemy either. Lop off the oaths of a man, and you have clipt the wings of his anger, you have smothered all his passion. Swearing, it is said, is as the wind to wrath. Lower the sails; no need of sails, when there is no wind. If then we do not clamor, and do not swear, we have cut the sinews of passion. And if you doubt this, just put it to experiment. Impose it as a law upon the passionate man that he shall never swear, and you will have no necessity of preaching moderation to him. So the whole business is finished. For even though you do not forswear yourselves [yet], by swearing at all, do you not know in what absurd consequences you involve yourselves— binding yourselves to an absolute necessity and as with a cord, and putting yourselves to all manner of shifts, as men studying how to rescue their soul from an evil which there is no escaping, or, failing of that, obliged [by that self-imposed necessity] to spend your life thenceforth in vexation, in quarrels, and to curse your wrath? But all is in vain, and to no purpose. Threaten, be peremptory (διόρισαι), do all, whatever it be, without swearing; [so]: it is in your power to reverse (ἀ ναλὕσαι) both what you have said and what you have done if you have the mind. Thus on the present day I must needs speak more gently to you. For since you have heard me, and the greater part of the reformation is achieved by you, now then let us see for what purpose the taking of oaths was introduced, and why allowed to be. In relating to you their first origin, and when they were conceived, and how, and by whom we shall give you this account in requital for your obedience. For it is fit that he who has made his practice right, should be taught the philosophy of the matter, but he who is not yet doing the right, is not worthy to be told the history.
They made many covenants in Abraham's time, and slew victims, and offered sacrifices, and as yet oaths were not. Whence then did they come in? When evil increased, when all was confusion, upside down, when men had turned aside to idolatry: then it was, then, when men appeared no longer worthy to be believed, that they called God as witness, as if thereby giving an adequate surety for what they said. Such in fact is the Oath: it is a security where men's principles cannot be trusted. So that in the indictment of the swearer the first charge is this—that he is not to be trusted without a surety, and a great surety too: for such is the exceeding faithlessness, that they ask not man as surety, but will needs have God! Secondly, the same charge lies against him who receives the oath: that, in a question of compact, he must drag in God for warranty, and refuse to be satisfied unless he get Him. O the excessive stupidity, the insolence of such conduct! Thou, a worm, earth and dust, and ashes, and vapor, to drag in your Lord as the surety, and to compel the other to drag Him in likewise! Tell me, if your servants were disputing with each other, and exchanging assurances with each other, and the fellow-servant should declare that for his part he would not be satisfied till he had their common master given him for surety, would he not have stripes given him without number, and be made to know that the master is for other purposes, and not to be put to any such use as this? Why do I speak of a fellow-servant? For should he choose any respectable person, would not that person consider it an affront? But I do not wish to do this, say you. Well: then do not compel the other to do so either: since where men only are in question, this is done— if your party says, “I give such an one as my surety,” you do not allow him. “What then,” say you, “am I to lose what I have given?” I am not speaking of this; but that you allow him to insult God. For which reason greater shall be the inevitable punishment to him who forces the oath upon another, than to him who takes it: the same holds with regard to him who gives an oath when no one asks him. And what makes it worse, is, that every one is ready to swear, for one farthing, for some petty item, for his own injustice. All this may be said, when there is no perjury; but if perjury follow in the train, both he that imposes and he that takes the oath have turned everything upside down. “But there are some things,” you will say, “which are unknown.” Well take these into account, and do nothing negligently; but, if you do act negligently, take the loss to yourself as your punishment. It is better to be the loser thus, than in a very different way. For tell me— you force a man to take an oath, with what expectation? That he will forswear himself? But this is utter insanity; and the judgment will fall upon your own head; better you should lose your money, than he be lost. Why act thus to your own detriment, and to the insulting of God? This is the spirit of a wild beast, and of an impious man. But you do this in the expectation that he will not forswear himself? Then trust him without the oath. “Nay, there are many,” you reply, “who in the absence of an oath would presume to defraud; but, once the oath taken, would refrain.” You deceive yourself, man. A man having once learned to steal, and to wrong his neighbor, will presume full oft to trample upon his oath; if on the contrary he shrinks from swearing, he will much more shrink from injustice. “But he is influenced against his will.” Well then, he deserves pardon.
Source: Homilies on Acts (New Advent)