Acts 7:6-8

6This is what God said to him: “Your descendants will live in a foreign country for 400 years. The people in that country will cause your descendants to be their slaves. They will be very cruel to them.

7But I will punish those people who cause your descendants to work as slaves for them. After I have done that, your descendants will leave that country. They will come to this place and worship me here.” That is what God said to Abraham.

8Then God made an covenant with Abraham that his descendants would be his special people. God said, “You must circumcise all your baby boys.” Later, Abraham became the father of Isaac. Abraham circumcised Isaac when he was eight days old. Then Isaac became the father of Jacob. Jacob himself had 12 sons. These sons became the 12 ancestors of the families of Israel.