Numbers 1:48

46all those who were counted were six hundred three thousand five hundred fifty.

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

48For the LORD spoke to Moses, saying,

49“Only the tribe of Levi you shall not count, neither shall you take a census of them among the children of Israel;

50but appoint the Levites over the Tabernacle of the Testimony, and over all its furnishings, and over all that belongs to it. They shall carry the tabernacle and all its furnishings; and they shall take care of it, and shall encamp around it.