Genesis 15:13-16

13Then the Lord said to Abram, ‘Be sure of this: Your descendants will live in a foreign country. They will be strangers there. People will do bad things to them and they will become slaves. This will continue for 400 years.

14But I will punish the people of that country who give them trouble. After this, your descendants will leave that country. They will take many valuable things with them.

15But as for you, Abram, you will have a long life. When you die, you will have peace in your mind.

16After four generations, your descendants will come back here to Canaan. At that time, I will punish the Amorites because they do very bad things. But the time has not yet arrived that I will punish them.’