Ezekiel 39:12-16

For seven months the house of Israel will be burying them, in order to cleanse the land. All the people of the land will bury them, and it will bring them renown on the day that I show my glory, declares the Lord GOD. They will set apart men to travel through the land regularly and bury those travelers remaining on the face of the land, so as to cleanse it. At the end of seven months they will make their search. And when these travel through the land and anyone sees a human bone, then he shall set up a sign by it, till the buriers have buried it in the Valley of Hamon-gog. (Hamonah is also the name of the city.) Thus shall they cleanse the land.