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

Jamieson-Fausset-Brown Bible Commentary

26. when your children shall say, . What mean ye by this service-Independently of some observances which were not afterwards repeated, the usages practised at this yearly commemorative feast were so peculiar that the curiosity of the young would be stimulated, and thus parents had an excellent opportunity, which they were enjoined to embrace, for instructing each rising generation in the origin and leading facts of the national faith.

Matthew Henry's Concise Commentary

12:21-28 That night, when the first-born were to be destroyed, no Israelite must stir out of doors till called to march out of Egypt. Their safety was owing to the blood of sprinkling. If they put themselves from under the protection of that, it was at their peril. They must stay within, to wait for the salvation of the Lord; it is good to do so. In after-times they should carefully teach their children the meaning of this service. It is good for children to ask about the things of God; they that ask for the way will find it. The keeping of this solemnity every year was, 1. To look backward, that they might remember what great things God had done for them and their fathers. Old mercies, to ourselves, or to our fathers, must not be forgotten, that God may be praised, and our faith in him encouraged. 2. It was designed to look forward, as an earnest of the great sacrifice of the Lamb of God in the fulness of time. Christ our passover was sacrificed for us; his death was our life.