Numbers 31:6 (BSB)

And Moses sent the thousand from each tribe into battle, along with Phinehas son of Eleazar the priest, who took with him the vessels of the sanctuary and the trumpets for signaling.

From Numbers 31. Also in the ESV.

Commentary on Numbers 31:6

• John Gill (Reformed Baptist), Exposition of the Old and New Testaments on Numbers 31:6: And Moses sent them to the war,.... Being mustered and armed: a thousand of every tribe, them and Phinehas the son of Eleazar the priest to the war; which looks as if Phinehas was the general of this army; for Moses went not to the war, and no mention is made of Joshua, nor might it be proper for him, he being the successor of...
• Jamieson-Fausset-Brown (Reformed), Commentary Critical and Explanatory on the Whole Bible on Numbers 31:6: Moses sent . . . Eleazar the priest, to the war--Although it is not expressly mentioned, it is highly probable that Joshua was the general who conducted this war. The presence of the priest, who was always with the army (Deu 20:2), was necessary to preside over the Levites, who accompanied the expedition, and to inflame the courage of the combatants by his sacred services and counsels.
• Geneva Bible Notes (Reformed), Geneva Bible Study Notes on Numbers 31:6: And Moses sent them to the war, a thousand of [every] tribe, them and Phinehas the son of Eleazar the priest, to the war, with the holy instruments, and the trumpets to blow in his hand. (b) For his great zeal that he bare for the Lord, .
• Keil & Delitzsch (Lutheran), Biblical Commentary on the Old Testament on Numbers 31:3-6: Num 31:3-6 To carry out this revenge, Moses had 1000 men of each tribe delivered (ימּסרוּ, see at Num 31:16) from the families (alaphim, see Num 1:16) of the tribes, and equipped for war; and these he sent to the army (into the war) along with Phinehas the son of Eleazar the high priest, who carried the holy vessels, viz., the alarm-trumpets, in his hand.