Exodus 12:24-26

"And ye shall observe this thing for an ordinance to thee and to thy sons for ever. And 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. And it shall come to pass, when your children shall say unto you, What mean ye by this service?" - Exodus 12:24-26 KJV