Matthew 5:33-37 Douay-Rheims
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.