Exodus 13:5; Exodus 13:10

5 "It shall be when the LORD brings you to the land of the Canaanite, the Hittite, the Amorite, the Hivite and the Jebusite, which He swore to your fathers to give you, a land flowing with milk and honey, that you shall observe this rite in this month.

10 "Therefore, you shall keep this ordinance at its appointed time from year to year.