C. F. Keil and Franz Delitzsch on Numbers 19:11-13

Num 19:11-13

Whoever touched a corpse, “with regard to all the souls of men,” i.e., the corpse of a person, of whatever age or sex, was unclean for seven days, and on the third and seventh day he was to cleanse himself (התחטּא, as in Num 8:21) with the water (בּו refers, so far as the sense is concerned, to the water of purification). If he neglected this cleansing, he did not become clean, and he defiled the dwelling of Jehovah (see at Lev 15:31). Such a man was to be cut off from Israel (vid., at Gen 17:14).