출애굽기 12:38의 Kabbalah

Erev/night - as you say "and also an erev rav went up with them" (Ex. 12:38), since all those pure travails are the ones that mix [mit'arev] with the forces of the night. And this is why there is no obligation regarding the night prayer, because no person can say it like Ya'akov, who was the master of the dwelling, and was the [only] one who could say it properly.