Leviticus 15:2-6

“Speak to the sons of Israel, and say to them, ‘When any man has a discharge from his body, his discharge is unclean.

This, moreover, shall be his uncleanness in his discharge: it is his uncleanness whether his body allows its discharge to flow or whether his body obstructs its discharge.

Every bed on which the man with the discharge lies becomes unclean, and everything on which he sits becomes unclean.

Anyone, moreover, who touches his bed shall wash his clothes and bathe in water and be unclean until evening;

and whoever sits on the thing on which the man with the discharge has been sitting, shall wash his clothes and bathe in water and be unclean until evening.