Numbers 1:47

44 These [are] those that were numbered, which Moses and Aaron numbered, and the princes of Israel, [being] twelve men: each one was for the house of his fathers.

45 So were all those that were numbered of the children of Israel, by the house of their fathers, from twenty years old and upward, all that were able to go forth to war in Israel;

46 Even all they that were numbered, were six hundred thousand and three thousand and five hundred and fifty.

47 But the Levites, after the tribe of their fathers, were not numbered among them.

48 For the LORD had spoken to Moses, saying,

49 Only thou shalt not number the tribe of Levi, neither take the sum of them among the children of Israel:

50 But thou shalt appoint the Levites over the tabernacle of testimony, and over all its vessels, and over all things that [belong] to it: they shall bear the tabernacle, and all its vessels, and they shall minister to it, and shall encamp around the tabernacle.