1Ch 25:1
25:1 Moreover David and the captains of the host {a} separated
     to the service of the sons of Asaph, and of Heman, and of
     Jeduthun, who should prophesy with harps, with psalteries,
     and with cymbals: and the number of the workmen according
     to their service was:

     (a) The singers were divided into 24 courses, so that every
         course or order contained twelve, and in all there were
         288, as in @1Ch 25:7.

1Ch 25:3
25:3 Of Jeduthun: the sons of Jeduthun; Gedaliah, and Zeri, and
     Jeshaiah, Hashabiah, and Mattithiah, {b} six, under the
     hands of their father Jeduthun, who {c} prophesied with a
     harp, to give thanks and to praise the LORD.

     (b) Of which one is not here numbered.
     (c) Meaning, psalms and songs to praise God.

1Ch 25:8
25:8 And they cast lots, {d} ward against [ward], as well the
     {e} small as the great, the teacher as the scholar.

     (d) Who should be in every company and course.
     (e) Without respect to age or cunning.

1Ch 25:9
25:9 Now the first lot came forth for Asaph to {f} Joseph: the
     second to Gedaliah, who with his brethren and sons [were]
     twelve:

     (f) So that he served in the first turn and the rest every
         one as his turn followed in order.