Charles Ellicott Commentary 1 Chronicles 6:31

"And these are they whom David set over the service of song in the house of Jehovah, after that the ark had rest." — 1 Chronicles 6:31 (ASV)

Set over the service of song. —Literally, made stand by the sides (hands) of song, as if to minister to the sacred music. (Compare 1 Chronicles 25:2–3, where the same peculiar phrase recurs, and Psalm 123:2, as the eyes of slaves are unto the hand of their Lord. Compare also the common heading of the Psalms, “to the conductor or precentor; ” Authorized Version, chief musician.)

In the house of the Lord. —In David’s time, a tent, as next verse declares.

After that the ark had rest. —Perhaps locative: at the resting-place of the Ark . From the time of its capture by the Philistines (2 Samuel 6:17), the Ark had no certain dwelling until it was lodged in the tent which David spread for it on Mount Zion.