Numbers 2:34

2:34 So the Israelites did according to all that the Lord commanded Moses; that is the way they camped under their standards, and that is the way they traveled, each with his clan and family.

Numbers 31:19

Purification After Battle

31:19 “Any of you who has killed anyone or touched any of the dead, remain outside the camp for seven days; purify yourselves and your captives on the third day, and on the seventh day.