וַיַּעֲמִידֵ֣ם לָעַ֣ד לְעוֹלָ֑ם חָק־נָ֝תַ֗ן וְלֹ֣א יַעֲבֽוֹר׃
Itinatag Niya sila magpakailan-kailanman; nagtakda Siya ng batas na hindi lalabagin.
Rashi
He issued a decree to them, that this one should serve by day and that one should serve by night. which will not change That decree.