This verse seems to imply that the soldiers, as distinct from the officers (compare Numbers 31:49), did not make any offering from their plunder. Of course besides the gold there would be much spoil of less precious materials; see Numbers 31:20, Numbers 31:22.

For the men of war had taken spoil, every man for himself. And which he kept for himself, and did not deliver in with the prey or booty, which was brought to Moses and Eleazar, the sum of which was taken by them; and this seems to confirm what has been hinted, that, as each soldier had taken spoil for himself, so everyone contributed his quota towards this freewill offering to the Lord.

(For the men of war had taken spoil, every man for {r} himself.)

(r) And gave no portion to their captains.

31:48-54 The success of the Israelites had been very remarkable, so small a company overcoming such multitudes, but it was still more wonderful that not one was slain or missing. They presented the gold they found among the spoils, as an offering to the Lord. Thus they confessed, that instead of claiming a reward for their service, they needed forgiveness of much that had been amiss, and desired to be thankful for the preservation of their lives, which might justly have been taken away.