Only thou shalt not number the tribe of Levi, neither take the sum of them among the children of Israel:
Numbers 2:33
And the Levites have not numbered themselves in the midst of the sons of Israel, as Jehovah hath commanded Moses.
Numbers 26:62
And their numbered ones are three and twenty thousand, every male from a son of a month and upwards, for they have not numbered themselves in the midst of the sons of Israel; for an inheritance hath not been given to them in the midst of the sons of Israel.