Hebrews 6:16-18

Revised Standard Version

¹⁶ Men indeed swear by a greater than themselves, and in all their disputes an oath is final for confirmation. ¹⁷ So when God desired to show more convincingly to the heirs of the promise the unchangeable character of his purpose, he interposed with an oath, ¹⁸ so that through two unchangeable things, in which it is impossible that God should prove false, we who have fled for refuge might have strong encouragement to seize the hope set before us.