Kabbalah zu Schemot 23:12

And there is the mark of Shad"ai, that is Metatro"n as servant, and many servants are dependent on him, that he is the appointed one on those who are servants in order to receive a reward (see Avot 1:3). Metatro"n and his servants are appointed over them. And regarding them it is said: "so that your ox and your donkey and your slave and your female slave rest" (Exodus 23:12). But those who observe/follow/serve the commandments without the intention of receiving a reward, those are the children of the King and the Matronita. And they are the crowns and the adornments on the head, that serve on the common days. And regarding them it is said "and those who make use of the crown disappear" (Avot 1:13) and "the stranger that comes" on them "will die" since the Shabatot are called for the servants.