17 And the Lord spoke unto Moses and unto Aaron, saying,
18 Ye shall not cut off the tribe of the families of Kohath from among the Levites,
19 but thus do unto them that they may live, and not die, when they approach unto the holy of holies: Aaron and his sons shall come and place each one of them in his ministry and to his burden.
20 They shall not go in to see when the holy things are covered, lest they die.
21 And the Lord spoke unto Moses, saying,
22 Take also the sum of the sons of Gershon, throughout the houses of their fathers, by their families;
23 from thirty years old and upward until fifty years old shalt thou number them, all that enter in to the host to do work in the tabernacle of the testimony.