But let your communication be, Yea, yea; Nay, nay: for whatsoever is more than these cometh of evil.
Note 20 at Mt 5:37: We should not have to use an oath to validate what we say. If we do, that's a reflection on our integrity. If we each have a good name (Pr 22:1), our "yes" or "no" should be sufficient. God's words are sure (Ps 18:30, 19:7, 89:34, 111:7, 138:2; and 2Co 1:20), and to be Christ-like (like Christ) and godly (like God), ours must be too.