che.leph marks the return or compensation connected with the Levites’ service and support.

As a preposition, it marks the relation between the Levites’ service and the provision given in return: the tithe is connected with their service in Numbers 18:21, and wages are connected with that service in Numbers 18:31.

1. Preposition marking provision in return for service · dominant

   Both occurrences are tagged as prepositions and link provision to service. In Numbers 18:21 the APB renders the clause "as an inheritance in return for their service," while in Numbers 18:31 it renders wages "in return for your service in the tent of meeting."

   Numbers 18:21Numbers 18:31

In the Anselm Project Bible: The APB presents the relation with "in return for" in both verses.