Numbers 31:50

The “chains” were “armlets” 2 Samuel 1:10. The “rings” were “finger-rings,” or “seal-rings;” and the “tablets” were worn suspended from the neck Exodus 35:22.

To make an atonement for our souls before the Lord - Compare Exodus 30:11. The atonement was not for any special offence committed (which would have called for a sacrifice of blood-shedding), but rather like the half-shekel given at the census in the Book of Exodus (loc. cite), was an acknowledgment of having received undeserved mercies. These, if unacknowledged, would have entailed guilt on the soul.