اَلْعَدَد 31:19

وَأَمَّا أَنْتُمْ فَٱنْزِلُوا خَارِجَ ٱلْمَحَلَّةِ سَبْعَةَ أَيَّامٍ، وَتَطَهَّرُوا كُلُّ مَنْ قَتَلَ نَفْسًا، وَكُلُّ مَنْ مَسَّ قَتِيلًا، فِي ٱلْيَوْمِ ٱلثَّالِثِ وَفِي ٱلسَّابِعِ، أَنْتُمْ وَسَبْيُكُمْ.

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.