Because the LORD kept a vigil that night to bring them out of the land of Egypt, this same night is to be a vigil to the LORD, to be observed by all the Israelites for the generations to come.
KJV
It [is] a night to be much observed unto the LORD for bringing them out from the land of Egypt: this [is] that night of the LORD to be observed of all the children of Israel in their generations.
ASV
It is a night to be much observed unto Jehovah for bringing them out from the land of Egypt: this is that night of Jehovah, to be much observed of all the children of Israel throughout their generations.