Albert Barnes Commentary Deuteronomy 18:6-8

"And if a Levite come from any of thy gates out of all Israel, where he sojourneth, and come with all the desire of his soul unto the place which Jehovah shall choose; then he shall minister in the name of Jehovah his God, as all his brethren the Levites do, who stand there before Jehovah. They shall have like portions to eat, besides that which cometh of the sale of his patrimony." — Deuteronomy 18:6-8 (ASV)

These verses presuppose that only part of the Levites will be residing and officiating at the sanctuary, while the others, of course, live in their own homes in the Levitical cities or are “sojourning” elsewhere; compare the marginal references. But if any Levite, out of love for the service of the sanctuary, chose to go to it when he could have resided in his own home, he was to have his share in the support provided for those ministering in the order of their service (Deuteronomy 18:8).

Besides what comes from the sale of his patrimony — The Levites indeed had no part nor inheritance with Israel, but they might individually possess property, and in fact, often did so (Compare 1 Kings 2:26; Jeremiah 32:7; Acts 4:36). The Levite who desired to settle at the sanctuary would probably sell his patrimony when leaving his former home. The text directs that, despite any such private resources, he should rightfully enjoy his share of the provisions for the ministers at the sanctuary. As he was waiting at the altar, he should be a partaker with the altar (1 Corinthians 9:13).