Where did David direct the sons of Asaph to worship with instruments?
Ezra 3:10 (ESV)
10And when the builders laid the foundation of the temple of the LORD, the priests in their vestments came forward with trumpets, and the Levites, the sons of Asaph, with cymbals, to praise the LORD, according to the directions of David king of Israel.
David assigned the sons of Asaph to worship with musical instruments in1 Chronicles 16:5, 1 Chronicles 25:1.
10 And when the builders laid the foundation of the temple of the LORD, the priests in their vestments came forward with trumpets, and the Levites, the sons of Asaph, with cymbals, to praise the LORD, according to the directions of David king of Israel.