Moses sent them off to war, a thousand from each tribe, and also Phinehas son of Eleazar, who went as priest to the army, in charge of holy vessels and the signaling bugles.
They took it all--captives and booty and plunder--back to Moses and Eleazar the priest and the company of Israel where they were camped on the Plains of Moab, at Jordan-Jericho.
They're the ones who, under Balaam's direction, seduced the People of Israel away from GOD in that mess at Peor, causing the plague that hit GOD's people.
"Now here's what you are to do: Pitch tents outside the camp. All who have killed anyone or touched a corpse must stay outside the camp for seven days. Purify yourselves and your captives on the third and seventh days.
and anything else that can survive fire--must be passed through the fire; then it will be ritually purified. It must also be ritually washed in the Water-of-Cleansing. Further, whatever cannot survive fire must be put through that water.
Tax the congregation's half-share at the rate of one life out of fifty, whether persons, cattle, donkeys, sheep, goats, or other animals. Give this to the Levites who are in charge of the care of GOD's Dwelling."
From the half-share going to the People of Israel, Moses, just as GOD had instructed him, picked one out of every fifty persons and animals and gave them to the Levites, who were in charge of maintaining GOD's Dwelling.
We've brought offerings to GOD from the gold jewelry we got--armlets, bracelets, rings, earrings, ornaments--to make atonement for our lives before GOD."
Moses and Eleazar took the gold from the commanders of thousands and hundreds and brought it to the Tent of Meeting, to serve as a reminder for the People of Israel before GOD.