זוהר שמות — דף רא ע”ב

Parasha Vayakhel — folio 201b. The Zohar describes the cycle of governance of night and day: as night enters, a herald calls the rulers of the night each to their place, and likewise at dawn for the rulers of the day. At each transition, one host departs and another enters in an orderly fashion. God arranged creation so that the supernal spirits fulfill their roles in a wondrous order. There are different firmaments for different hours, each governed by a particular appointed one.