'Acting' in the Bible

Of the sons of Asaph: Zaccur and Joseph and Nethaniah and Asharelah, sons of Asaph; under the direction of Asaph, acting as a prophet under the orders of the king;

Of Jeduthun: the six sons of Jeduthun, Gedaliah and Zeri and Jeshaiah, Hashabiah and Mattithiah; under the direction of their father Jeduthun who, acting as a prophet, with corded instruments gave praise and glory to the Lord.