Leviticus 15:16

And if any man’s seed of copulation go out from him, then he shall wash all his flesh in water, and be unclean until the even.

Cross-reference

Leviticus 15:5 gives the same washing requirement for touching the bed of a man with an emission — a parallel rule in the same chapter.

Leviticus 22:4 applies the same discharge uncleanness to priests, barring them from holy food — a specific extension of the purity law.

Deuteronomy 23:10 adds that a man with nocturnal emission must stay outside the camp until evening, extending the law to military settings.

Deuteronomy 23:11 specifies that after bathing at evening he may re-enter the camp, clarifying the timing of cleansing.

1 Samuel 20:26 shows Saul interpreting David's absence as due to ceremonial uncleanness, applying the same law.