Numbers 19:16

19:16 And whoever touches the body of someone killed with a sword in the open fields, or the body of someone who died of natural causes, or a human bone, or a grave, will be unclean seven days.

Numbers 19:18

19:18 Then a ceremonially clean person must take hyssop, dip it in the water, and sprinkle it on the tent, on all its furnishings, and on the people who were there, or on the one who touched a bone, or one killed, or one who died, or a grave.