Today I will type up the Commentary of Cornelius A Lapide on S. Matthew 5:33-37
33. Again you have heard that it was said to them of old, Thou shalt not forswear thyself: but thou shalt perform thy oaths to the Lord.
34. But I say to you not to swear at all, neither by heaven, for it is the throne of God:
35. Nor by the earth, for it is his footstool: nor by Jerusalem, for it is the city of the great king:
36. Neither shalt thou swear by thy head, because thou canst not make one hair white or black.
37. But let your speech be yea, yea: no, no: and that which is over and above these, is of evil.
But I say to you not to swear at all. "From this passage the Pelagians taught that no oath was lawful for Christians, as we see from the Council of Constance, and the Anabaptists of the present day hold the same opinion, who will not swear in a trial at the bidding of a judge. But this is an error of faith, which the ...example of God Himself , of S. Paul, and the saints condemn as is plain from Psalms 109:4, Rom 1:9, etc. ...An oath is an honor to God as the prime Verity, because he who swears appeals to God, who is infallible Truth, as his Witness. Therefore an oath is an act of religion, and the highest worship, provided that it be done in truth.
You will ask, Why then does Christ say, swear not at all? S. Bernard says that this is not a precept, but only of counsel...So as not to fall into perjury through the habit of swearing, as often happens.
...[Another reason is] Because the trustworthiness and honesty of men, especially of believers and Christians, ought to be such, that things not sworn to can be believed.
...S. Augustine says "False swearing is destructive, true swearing is perilous, swearing not at all is safe." ... Just as it is a moral evil, per se, to kill any one, there are circumstances in which it is permissible, dutiful, and even laudable So it is with an oath.
Neither by heaven for it is the throne of God,: Nor by the earth for it is his footstool: Nor by Jerusalem, for it is the city of the great king. Christ here teaches that he who swears by heaven or earth, swears by God their creator... [by Jerusalem] The meaning is; Do not swear by the saints, the holy city of Jerusalem, nor by other sacred things, nor by your own possessions, or by any other creature, for they all belong to God, who is present in them all and who alone has complete power over them. In like manner, he who swears by creatures swears by God...
Wrongly, do the modern heretics, specifically Augustine Marloratus, say "Just as of old anyone who swore by another idol, detracted to the extent from God's rights, because they put something else in the place of Him who knows hearts and judges souls, so today, those who swear by angels and by dead saints, vainly attach to them the Divinity of which they have deprived from God." But this is an error and a heresy... Paul (1 Cor. 15:31) swears by the glory of the Corinthians, as is plain from the Greek text. The honor of the saints is the honor of God. For God made them saints; therefore one who swears by the saints swears by their God and Sanctifier.
Neither shalt thou swear by thy head, because thou canst not make one hair white or black. This means: Do not think that you are allowed to swear by your head because it is yours, and subject to you and your full control to use as you wish, for any purpose, even to bring down curses upon it by an oath if you perjure yourself; because in fact, your head is not your own, but God's. So you cannot make even one hair of your head white or black; that is for God alone to do. Therefore anyone who swears by their head, swears by God who made it; moreover-horrible thought-such a man is asking God to accept his very herd and life as a pledge, so that if he commits perjury, God will punish him by demanding his head and his life.
But let your speech be yea, yea: no, no: (simple affirmation or negation) and that which is over and above these (Greek "excessive": the Syrian version "what is added beyond these") is of evil. The Hebrew translated is "truly; truly, no, no."...
Hence S. Bernard praises Theobald for his simple truthfulness. "for him, as it is said, speaking simply is as good as swearing, and a trifling lie is accounted grave perjury..."
Is of evil- The Greek has "is from the evil one." Evil here may be taken in the masculine or the neuter gender. If masculine, of evil means "from the devil," who, as a ringleader of all iniquity, incites thee to swear falsely, which is the sin of perjury. If of evil is neuter, it means "cometh of vice." The custom of wearing arises from your own vice of levity or irreverence. Franz Lucas admits this: of evil, he says, means from a habit of swearing needlessly and lightly, or falsely and deceitfully. Again, of evil means from a habit of swearing that originates in human mistrust. Since it seemed that men would not believe one another unless they swore.
