2 Chronicles 35:15

And the sons of Asaph the psalm-singers [were] at their post according to the commands of David, and Asaph, and Æman, and Idithom, the prophets of the king: also the chiefs and the porters of the several gates;—it was not for them to stir from the service of the holy things, for their brethren the Levites prepared for them.