1 Chronicles 23:3-7

Now the Levites were counted from thirty years old and upward, and their number by head count of men was thirty-eight thousand.

Of these, twenty-four thousand were to oversee the work of the house of the Lord; and six thousand were officers and judges,

and four thousand were gatekeepers, and four thousand were praising the Lord with the instruments which David made for giving praise.

David divided them into divisions according to the sons of Levi: Gershon, Kohath, and Merari. Gershonites

Of the Gershonites there were Ladan and Shimei.