Leviticus 15:16

And if any man's seed of copulation go out from him,.... Not in lawful cohabitation, nor voluntarily, but involuntarily, as Aben Ezra observes; not through any disorder, which came by an accident, or in any criminal way, but through a dream, or any lustful imagination; what is commonly called nocturnal pollution c;

then he shall wash all his flesh in water, and be unclean until the even; and so the Egyptian priests, when it happened that they were defiled by a dream, they immediately purified themselves in a laver d so the Jewish priests did when the like happened to them asleep in the temple e; see Deuteronomy 23:10.

c "---- noctem flumine purgas." Pers. Satyr. 2. d Chaeremon. apud Porphyr. de Abstinentia, l. 4. c. 7. e Misn. Tamid. c. 1. sect. 1.