Deuteronomy 15:16

If a slave elect to remain in the master's service instead of accepting release, a formal compact must be made to that effect. In Exodus 21:6 the ceremony is performed in public before the magistrates; here it seems to be private. The boring of the ear and the fastening it to the doorpost with the awl signified that the person was permanently attached to the house and was bound to obey the words of his master: cp. on Exodus 21:6.

19, 20. In Numbers 18:15 the firstlings of clean beasts are the perquisite of the priests. Here they are to be eaten by the owner and. his household annually at the central sanctuary. Much ingenuity has been expended in the attempt to reconcile these two regulations. The simplest explanation is that they belong to different stages of legislation.