Leviticus 15:8
"And if he that hath the issue spit upon him that is clean; then he shall wash his clothes, and bathe himself in water, and be unclean until the even."
Cross References (ranked by relevance)
Jude 1:4
For there are certain men crept in unawares, who were before of old ordained to this condemnation, ungodly men, turning the grace of our God into lasciviousness, and denying the only Lord God, and our Lord Jesus Christ.
Isaiah 1:16
Wash you, make you clean; put away the evil of your doings from before mine eyes; cease to do evil;
James 4:8
Draw nigh to God, and he will draw nigh to you. Cleanse your hands, ye sinners; and purify your hearts, ye double minded.