Hebrews 6:13-15

For when God made the promise to Abraham, He swore [an oath] by Himself, since He had no one greater by whom to swear, saying, “I WILL SURELY BLESS YOU AND I WILL SURELY MULTIPLY YOU.” [Gen 22:16, 17] And so, having patiently waited, he realized the promise [in the miraculous birth of Isaac, as a pledge of what was to come from God].