C. F. Keil and Franz Delitzsch on 1 Chronicles 26:29

1Ch 26:29 The officials for the external business. - 1Ch 26:29. “As to the Izharites, Chenaniah (see on 1Ch 15:22) with his sons was for the outward business over Israel for scribes and judges.” According to this, the external business of the Levites consisted of service as scribes and judges, for which David had set apart 6000 Levites (1Ch 23:4). Without sufficient reason, Bertheau would refer the external business to the exaction of the dues for the temple, because in Neh 11:16 ההיצנה המּלאכה for the temple is spoken of. But it does not at all follow that in our verse the external work had any reference to the temple, and that the scribes and judges had only this narrow sphere of action, since here, instead of the house of God, ישׂראל על is mentioned as the object with which the external service was connected.