And if a stranger shall sojourn among you, and will keep the passover unto the LORD; according to the ordinance of the passover, and according to the manner thereof, so shall he do: ye shall have one ordinance, both for the stranger, and for him that was born in the land.
If a stranger lives with you and wants to celebrate Passover, they should follow the rules and way it's done. You should have the same rules for both the stranger and those born in the land.