Numbers 18:1 - Joseph Benson’s Commentary on the Old and New Testaments

The Lord said unto Aaron Probably by Moses. Having, by the foregoing miracles, vindicated the honour and authority of the priesthood, God now lets Aaron know the importance of his office, wherein he was to behave with great care and circumspection, and withal he again declares what was the duty of the Levites, as distinct from that of the priests, from Num 18:1 to Numbers 18:8. And from thence he proceeds to tell them what maintenance he had settled upon both, for their encouragement in doing their duty. Thou and thy sons shall bear the iniquity of the sanctuary Shall suffer the punishment of all the usurpations, or pollutions of the sanctuary, or the holy things, by the Levites, or any of the people, because you have power from me to keep them all within their bounds. Thus the people are, in good measure, secured against their fears. Also they are informed that Aaron's high dignity was attended with great burdens, having not only his own but the people's sins to answer for; and therefore they had no such reason to envy him, if the benefits and dangers were equally considered. The iniquity of your priesthood That is, of all the errors committed by yourselves, or by you permitted in others, in things belonging to your priesthood.