Hebrews 6:17 in the King James Version
Where in God, willing more abundantly to shew unto the heirs of promise the immutability of his counsel, confirmed it by an oath:
Context
16 For men indeed swear by a greater one, and in every dispute of theirs the oath is final for confirmation.
17 In this way God, being determined to show more abundantly to the heirs of the promise the immutability of his counsel, interposed with an oath,
18 that by two immutable things, in which it is impossible for God to lie, we may have a strong encouragement, who have fled for refuge to take hold of the hope set before us.