Genesis 17:21-23

Revised Standard Version

²¹ But I will establish my covenant with Isaac, whom Sarah shall bear to you at this season next year.”

²² When he had finished talking with him, God went up from Abraham. ²³ Then Abraham took Ish′mael his son and all the slaves born in his house or bought with his money, every male among the men of Abraham’s house, and he circumcised the flesh of their foreskins that very day, as God had said to him.