Exodus 12:24-27

24And ye shall observe this thing for an ordinance to thee and to thy sons for ever.

25And it shall come to pass, when ye be come to the land which the Lord will give you, according as he hath promised, that ye shall keep this service.

26And it shall come to pass, when your children shall say unto you, What mean ye by this service?

27That ye shall say, It is the sacrifice of the Lord’s passover, who passed over the houses of the children of Israel in Egypt, when he smote the Egyptians, and delivered our houses. And the people bowed the head and worshipped.