Numbers 31:19
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. 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.
Numbers 31:19 belongs to the account of Israel's campaign against Midian, which stands as the record of judgment against a people wholly given over to evil, whose women were ordered destroyed because they could corrupt others. The surrounding passage in Numbers 31:7-47 records Israel's first taking of captives, when the army marched into Midian, slew all the males, and seized the women, children, flocks, and herds. On their return Moses rebuked them for disobeying God's command by sparing the grown women. They then killed all but the virgins and children, whom they reserved for adoption into the families of the nation.
The word rendered person for one who has been killed is the Hebrew nephesh, also spelled neh-phesh, meaning soul, and here meaning a person, or soul. The verse therefore speaks of people killed in battle as souls killed, and requires those who killed a soul to undergo purification on the third day and on the seventh day while abiding outside the camp seven days. By calling a killed person a killed soul, it presents the soul as a person who can die.