Matthew 5:33-34, 37

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

But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.