John Calvin Commentary Exodus 13:3

"And Moses said unto the people, Remember this day, in which ye came out from Egypt, out of the house of bondage; for by strength of hand Jehovah brought you out from this place: there shall no leavened bread be eaten." — Exodus 13:3 (ASV)

And Moses said to the people. He repeats what he had said more extensively in the previous chapter regarding the unleavened bread, not so much to instruct as to exhort them. For he had already explained the matter with such clarity that there was no need for further explanation; but it was useful to stimulate them, so that they might devote themselves with greater zeal to their duty, and especially so that their ardor would not, as usual, gradually abate after a longer lapse of time.

He therefore exhorts them that, after they came into the land, they should diligently observe what he had previously commanded.

And from the context here, it is clear that the two commands—concerning the sanctification of the first-born and the celebration of the Passover—had the same objective: namely, that their deliverance should retain the elect people in the special service of the true God.