Jamieson-Fausset-Brown on Numbers 31:13
Moses, and Eleazar the priest, . . . went forth to meet them without the camp--partly as a token of respect and congratulation on their victory, partly to see how they had executed the Lord's commands, and partly to prevent the defilement of the camp by the entrance of warriors stained with blood.
John Gill on Numbers 31:13
And Moses and Eleazar the priest, and all the princes of the congregation,.... Attended, no doubt, with a proper retinue:
went forth to meet them without the camp; partly to do honour to them, and to congratulate them on their victory, and partly to hinder them going into the camp directly, until they were purified; see Genesis 14:17.
John Calvin on Numbers 31:11-13
And they took all the spoil. It was a sign both of their disinterestedness and modesty, that they brought the booty, which they had taken in the ardor of battle, to Moses and Eleazar; nor was it a mere empty and pompous ceremony, as many boastingly parade the wealth which they desire to keep to themselves; but their intention was, to acquiesce in the determination of Moses as to its distribution. For, when Moses soon afterwards allots half of it to the people, they are so far from rebelling against his decision, that they do not even murmur. It is clear, then, that in this respect they were no less submissive than they had been when, at the outset, they took up arms, and boldly went forth to…
Read the whole note in the consoleKeil & Delitzsch on Numbers 31:13-18
Treatment of the Prisoners. - When Moses went out to the front of the camp with Eleazar and the princes of the congregation to meet the returning warriors, he was angry with the commanders, because they had left all the women alive, since it was they who had been the cause, at Balaam's instigation, of the falling away of the Israelites from Jehovah to worship Peor; and he commanded all the male children to be slain, and every woman who had lain with a man, and only the young girls who had hitherto had no connection with a man to be left alive. החיל פּקוּדי, lit., the appointed persons, i.e., the officers of the army, who were then divided into princes (captains) over thousands and hundreds.…