Exodus 13:5

13:5 When the Lord brings you to the land of the Canaanites, Hittites, Amorites, Hivites, and Jebusites, which he swore to your fathers to give you, a land flowing with milk and honey, then you will keep this ceremony in this month.

Exodus 23:15

23:15 You are to observe the Feast of Unleavened Bread; seven days you must eat bread made without yeast, as I commanded you, at the appointed time of the month of Abib, for at that time you came out of Egypt. No one may appear before me empty-handed.