John Gill Commentary Leviticus 22:7

"And when the sun is down, he shall be clean; and afterward he shall eat of the holy things, because it is his bread." — Leviticus 22:7 (ASV)

And when the sun is down he shall be clean. Having washed himself in water, otherwise not, though the sun may be set.

and shall afterwards eat of the holy things; the families of the priests lived upon.

because it [is] his food: his common food, his ordinary diet, that by which he subsists, having nothing else to live upon.

This being the ordination of God, that he which ministered about holy things should live on them; and these being his only substance, in compassion to him they were detained from him no longer than the evening; and this was done, to make him careful how he defiled himself, since thereby he was debarred of his ordinary meals.