Hastings' Dictionary of the Bible (1898)
NETH'INIM. Ezr 2:43, Ps 57:58. " This class are mentioned prominently in Ezra and Nehemiah as returning from the Captivity and constituting an official order. "They are mentioned in association with the Levites and priests, as well as with the porters and singers. 1 Chr 9:2; Ezr 7:24. They had been appointed for the first time by David, as far as we know, to do service for the Levites. Ezr 8:20. Some were therefore associated with the temple-service and dwelt at Jerusalem. Neh 11:21. As in the case of the priests and Levites, "no toll, tribute, or custom" was exacted from them, Ezr 7:24.
The service they performed was, no doubt, of a menial sort; still, their names were all carefully preserved. Ezr 8:20. It has been thought by many that the Gibeonites, Josh 9:27, who were made to do menial service for the congregation, and also the fifty captive Midianites, Num 31:47, who were portioned off to the Levites, occupied a similar position to the Nethinim. The name, however, is of a later date.