Exodus 12:40-42
12:40 Now the length of time the Israelites lived in Egypt was 430 years.
12:41 At the end of the 430 years, on the very day, all the regiments of the Lord went out of the land of Egypt.
12:42 It was a night of vigil for the Lord to bring them out from the land of Egypt, and so on this night all Israel is to keep the vigil to the Lord for generations to come.