Hebrews 6
16 Ref For men at all times make their oaths by what is greater; and any argument is ended by the decision of the oath.
17 Ref So that when it was God's desire to make it specially clear to those who by his word were to have the heritage, that his purpose was fixed, he made it more certain with an oath;
18 Ref So that we, who have gone in flight from danger to the hope which has been put before us, may have a strong comfort in two unchanging things, in which it is not possible for God to be false;