Numbers 31:19 in the King James Version
And do ye abide without the camp seven days: whosoever hath killed any person, and whosoever hath touched any slain, purify both yourselves and your captives on the third day, and on the seventh day.
Context
18 But all the girls, who have not known man by lying with him, keep alive for yourselves.
19 “Encamp outside of the camp for seven days. Whoever has killed any person, and whoever has touched any slain, purify yourselves on the third day and on the seventh day, you and your captives.
20 You shall purify every garment, and all that is made of skin, and all work of goats’ hair, and all things made of wood.”