They believed (after some doubts) the promises of God. And when the promises were not (yet) fulfilled, they considered God faithful who had promised (Hebrews 11:11). And when it was his time, God miraculously fulfilled his promises (Hebrews 11:12 and Genesis 15:5; Genesis 22:17). In this way Abraham and Sarah are models of the endurance in faith that will see the fulfillment of the 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.