John Chrysostom
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.
Or; of evil, that is, from their weakness to whom the Law permitted the use of an oath. Not that by this the old Law is signified to be from the Devil, but He leads us from the old imperfection to the new abundance.