What Does Exodus 12:42 Mean?

It was a night of watching by the LORD, to bring them out of the land of Egypt; so this same night is a night of watching kept to the LORD by all the people of Israel throughout their generations. Verse 42 names the Passover night from the divine perspective: it was "a night of watching" (Hebrew: leil shimurim, a night of vigil/keeping) by YHWH.

YHWH watched over Israel through the Passover night: the divine vigil corresponds to the blood-marked households waiting through the night while the destroyer moved through Egypt. The Passover night is doubly a vigil: YHWH watched over Israel, and Israel was to watch through the night (their own vigil of waiting and readiness to depart).

The corresponding human vigil, "a night of watching kept to the LORD by all the people of Israel throughout their generations", is the Passover night's perpetual religious character: not just annually commemorated but annually re-enacted as a night of vigil. The Passover seder's tradition of staying up through the night of the fourteenth of Nisan is rooted in verse 42's designation of the night as a vigil. Future generations who observe the Passover through the night are keeping watch as Israel kept watch in Egypt, and as YHWH kept watch over Israel.

The "throughout their generations" closes the Passover night's theological identity: this night, this watching, this divine-and-human vigil, is not a one-time experience but a permanent character of the fourteenth of Nisan for every generation of Israel. The Passover night is always the night of watching: the night YHWH watched over his people, and the night Israel watches in remembrance and renewal. Every Passover seder that runs through the night is the keeping of the original vigil.