1 Chronicles 16:37

So he left there before the ark of the covenant of the LORD Asaph and his brethren, to minister before the ark continually, as every day's work required:

2 Chronicles 8:14

And he appointed, according to the order of David his father, the courses of the priests to their service, and the Levites to their charges, to praise and minister before the priests, as the duty of every day required: the porters also by their courses at every gate: for so had David the man of God commanded.

Ezra 3:4

They kept also the feast of tabernacles, as it is written, and offered the daily burnt offerings by number, according to the custom, as the duty of every day required;

1 Chronicles 15:17-24

So the Levites appointed Heman the son of Joel; and of his brethren, Asaph the son of Berechiah; and of the sons of Merari their brethren, Ethan the son of Kushaiah;

1 Chronicles 16:4-6

And he appointed certain of the Levites to minister before the ark of the LORD, and to record, and to thank and praise the LORD God of Israel:

1 Chronicles 25:1-6

Moreover David and the captains of the host 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:

Treasury of Scripture Knowledge

Summary

So he left there before the ark of the covenant of the LORD Asaph and his brethren, to minister before the ark continually, as every day's work required:

Bible References

Before the ark

1 Chronicles 16:4
And he appointed certain of the Levites to minister before the ark of the LORD, and to record, and to thank and praise the LORD God of Israel:
1 Chronicles 15:17
So the Levites appointed Heman the son of Joel; and of his brethren, Asaph the son of Berechiah; and of the sons of Merari their brethren, Ethan the son of Kushaiah;
1 Chronicles 25:1
Moreover David and the captains of the host 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:

As every

2 Chronicles 8:14
And he appointed, according to the order of David his father, the courses of the priests to their service, and the Levites to their charges, to praise and minister before the priests, as the duty of every day required: the porters also by their courses at every gate: for so had David the man of God commanded.
Ezra 3:4
They kept also the feast of tabernacles, as it is written, and offered the daily burnt offerings by number, according to the custom, as the duty of every day required;

King James Version Public Domain