Exodus Exodus 12:21-51
The night the Passover became event faces two directions at once: behind, to YHWH's own vigil to bring Israel out of Egypt; ahead, to the watch Israel keeps for their generations — a feast still waiting, by its own grammar, for its last night.
Exodus Exodus 12:1-20
The blood goes on the outside of the door, where the family inside cannot see it — because it is a sign for God to read; and the verb the feast is named for does not mean to skip but to shelter, YHWH himself hovering over the marked house while the destroyer passes through Egypt.