Hebrews 11:11-12

11:11 By faith, even though Sarah herself was barren and he was too old, he received the ability to procreate, because he regarded the one who had given the promise to be trustworthy. 11:12 So in fact children were fathered by one man – and this one as good as dead – like the number of stars in the sky and like the innumerable grains of sand on the seashore.

Hebrews 11:17

11:17 By faith Abraham, when he was tested, offered up Isaac. He had received the promises, yet he was ready to offer up his only son.