Numbers 1:47-49

Young's Literal Translation

⁴⁷ And the Levites, for the tribe of their fathers, have not numbered themselves in their midst,

⁴⁸ seeing Jehovah speaketh unto Moses, saying,

⁴⁹ `Only, the tribe of Levi thou dost not number, and their sum thou dost not take up in the midst of the sons of Israel;