You shall observe this event [concerning Passover] as an ordinance for you and for your children forever.

When you enter the land which the Lord will give you, as He has promised, you shall observe this rite.

And when your children say to you, ‘What does this rite mean to you?’

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.

“Once a year Aaron is to perform the purification rite on the horns of the altar. Throughout your generations he is to perform the purification rite for it once a year, with the blood of the sin offering for atonement. The altar is especially holy to the Lord.”