民数记 31:19

你们要在营外驻扎七日；凡杀了人的，和一切摸了被杀的，并你们所掳来的人口，第三日，第七日，都要洁净自己，

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.