Ezra 8:20

Also of the Nethinims, whom David and the princes had
appointed for the service of the Levites
To wait upon them, and minister to them, as they did to the priests; some think those were the same with the Gibeonites, whom Joshua gave to the service of the sanctuary, and David confirmed; but others are of opinion these were different from them, and an addition to them:

two hundred and twenty Nethinims: all of them were expressed by
name;
in the history that Iddo sent of them to Ezra; and so the names of the Levites, though not here expressed, only the names of those they came with.