Adam Clarke on Numbers 18:20

I am thy part and thine inheritance - The principal part of what was offered to God was the portion of the priests, therefore they had no inheritance of land in Israel; independently of that they had a very ample provision for their support. The rabbins say twenty-four gifts were given to the priests, and they are all expressed in the law. Eight of those gifts the priests ate nowhere but in the sanctuary: these eight are the following: -

1. The flesh of the Sin-Offering, whether of beasts or fowls, Lev 6:25, Lev 6:26.

2. The flesh of the Trespass-Offering, Lev 7:1, Lev 7:6.

3. The Peace-Offerings of the congregation, Lev 23:19, Lev 23:20.

4. The remainder of the Omer or Sheaf, Lev 23:10, etc.

5. The remnants of the Meat-Offerings of the Israelites, Lev 6:16.

6. The two Loaves, Lev 23:17.

7. The Shew-Bread, Lev 24:9.

8. The Log of oil offered by the leper, Lev 14:10, etc.

Five of those gifts they ate only in Jerusalem: -

1. The breast and shoulder of the Peace-Offerings, Lev 7:31, Lev 7:34.

2. The Heave-Offering of the sacrifice of confession, Lev 7:12-14.

3. The Heave-Offering of the Nazarite's ram, Lev 6:17-20.

4. The Firstling of the clean beast, Num 18:15; Deu 15:19, Deu 15:20.

5. The First-Fruits, Num 18:13.

Five gifts were not due unto them by the law, but in the land of Israel only: -

1. The heave-offering or First-Fruits, Num 18:12.

2. The heave-offering of the Tithe, Num 18:28.

3. The Cake, Num 15:20.

These three were holy.

4. The first-fruits of the Fleece, Deu 18:4.

5. The Field of Possession, Numbers 35.

These two were common.

Five gifts were due unto them both within and without the land: -

1. The gifts of the Beasts Slain, Deu 18:3.

2. The redemption of the First-Born Son, Num 18:15.

3. The Lamb for the firstling of an ass, Exo 4:20; Numbers 18.

4. The restitution of that taken by violence from a stranger, Num 5:8.

5. All Devoted things, Num 18:14.

One gift was due unto them from the sanctuary: -

1. The skins of the burnt-offering, and all the skins of the other most holy things, Lev 7:8.

In all 24. See Ainsworth.

The gifts which the females of the priests' families had a part in were these: -

1. The heave-offering, or first-fruits.

2. The heave-offering of the tithe.

3. The cake.

4. The gifts of the beast, Deu 18:3.

5. The first of the fleece. - See Mishna, Tract. Biccurim, and Ainsworth on the Pentateuch.

Besides all this the priests had the tribute money mentioned Num 31:28, Num 31:29.