Hebrews 6:13-18 New American Bible (Revised Edition) (NABRE)
God’s Promise Immutable. 13 [a]When God made the promise to Abraham, since he had no one greater by whom to swear, “he swore by himself,” 14 and said, “I will indeed bless you and multiply” you. 15 And so, after patient waiting, he obtained the promise.[b] 16 Human beings swear by someone greater than themselves; for them an oath serves as a guarantee and puts an end to all argument. 17 So when God wanted to give the heirs of his promise an even clearer demonstration of the immutability of his purpose, he intervened with an oath, 18 so that by two immutable things,[c] in which it was impossible for God to lie, we who have taken refuge might be strongly encouraged to hold fast to the hope that lies before us.