Exodus 13:3-5

Moses said to the people, “Remember this day, the day you left Egypt. You were slaves in that land, but the LORD with his great power brought you out of it. You must not eat bread made with yeast. Today, in the month of Abib, you are leaving Egypt. The LORD will lead you to the land of the Canaanites, Hittites, Amorites, Hivites, and Jebusites. This is the land he promised your ancestors he would give you, a fertile land. There you must celebrate this feast during the first month of every year.