Sforno on Exodus 12:43/ספורנו על שמות י״ב:מ״ג

1זאת חקת הפסח, for the generations following the Exodus. The Torah legislates where it is to be eaten, by whom, how, when, etc. Only the requirement to put the blood of the sacrificial animal on the doorposts and to eat it in haste, ready for marching, were commandments applicable to the first such offering. All the other ordinances would apply for all future times. (compare Pessachim 96)