TSK · Numbers 1:47

from twenty years old and upward, all that are able to go forth to war in Israel, thou and Aaron shall number them by their hosts.

But the Levites were not numbered among the children of Israel; as Jehovah commanded Moses.

And Jehovah spake unto Moses, saying,

And they that were numbered of them were twenty and three thousand, every male from a month old and upward: for they were not numbered among the children of Israel, because there was no inheritance given them among the children of Israel.

But Levi and Benjamin counted he not among them; for the king's word was abominable to Joab.