Matthew 5:33-37 - The Sermon On The Mount: Taking Oaths
33 "Again ye heard that it was said to the ancients, You shall not swear falsely, but shall perform to the Lord your oaths;" 34 but I say to you, Swear not at all; neither by Heaven, because it is God's throne; 35 nor by the earth, because it is His footstool; nor by Jerusalem, because it is the Great King's city; 36 neither swear by your head, because you can not make one hair white or black. 37 But let your speech be, 'Yes, yes;' 'No, no;' and what is more than these is of the evil one.