Abraham did not believe God when he heard the promise of God: he laughed (Genesis 17:17). Sarah could not believe it either (Genesis 18:12) and she also laughed. But their unbelief turned into faith that God would fulfill his promise. There are different opinions on who is the subject of Hebrews 11:11: Abraham or Sarah. The text is clear that Sarah is the subject. By faith she gave herself—even though she was too old (Genesis 18:9–14)—to Abraham to receive the child of God’s promise.
11 C'est par la foi que Sara elle-même, malgré son âge avancé, fut rendue capable d'avoir une postérité, parce qu'elle crut à la fidélité de celui qui avait fait la promesse.