Numbers 31:5

5 And they numbered of the thousands of Israel a thousand of tribe, twelve thousands; armed for war.

Numbers 31:5 Meaning and Commentary

Numbers 31:5

So they were delivered out of the thousands of Israel
] Several thousands very probably offered themselves voluntarily to go to the war, or however were summoned together on this account, and out of them the following number was delivered of picked and chosen men:

a thousand [of every] tribe, twelve thousand armed for war;
which was but a small number to go against so considerable a nation and people; but this was done to show that the war was of the Lord, he would fight the battle, and give them victory, it being the same to him to do it with few as with many; and to encourage the people of Israel to believe the Lord would give them success against their many and powerful enemies in the land of Canaan, on the borders of which they now were.

Numbers 31:5 In-Context

3 And Moses spoke to the people, saying, Arm some of you, and set yourselves in array before the Lord against Madian, to inflict vengeance on Madian from the Lord.
4 Send a thousand of each tribe from all the tribes of the children of Israel to set themselves in array.
5 And they numbered of the thousands of Israel a thousand of tribe, twelve thousands; armed for war.
6 And Moses sent them away a thousand of every tribe with their forces, and Phinees the son of Eleazar the son of Aaron the priest: and the holy instruments, and the signal trumpets in their hands.
7 And they set themselves in array against Madian, as the Lord commanded Moses; and they slew every male.

The Brenton translation of the Septuagint is in the public domain.