the captains: That is, the chief of the several orders; not military captains. 1Ch 12:28, 1Ch 23:2, 1Ch 24:5-6; 2Ch 23:1, 2Ch 23:9
Asaph: 1Ch 6:33, 1Ch 6:39, 1Ch 6:44, 1Ch 15:16-19
prophesy: The word prophesy, here, seems to mean no more than praising God by singing inspired prophetical hymns. 1Ch 25:3; 1Sa 10:5; 2Ki 3:15; 1Co 14:24-26