Acts of the Apostles 7:6-8

God also told him that his descendants would live in a foreign land, where they would be oppressed as slaves for 400 years. ‘But I will punish the nation that enslaves them,’ God said, ‘and in the end they will come out and worship me here in this place.’ “God also gave Abraham the covenant of circumcision at that time. So when Abraham became the father of Isaac, he circumcised him on the eighth day. And the practice was continued when Isaac became the father of Jacob, and when Jacob became the father of the twelve patriarchs of the Israelite nation.