Jerome
Catena Aurea · Matthäusevangelium 5
Again, ye have heard that it hath been said by 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 Heaven; for it is God’s throne; Nor by the earth; for it is His footstool: neither by Jerusalem; for it is the city of the great King. Neither shalt thou swear by thy head, because thou canst not make one hair white or black. But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.
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, shews 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.