2 Chronicles 35:15

And the singers, the sons of Asaph, were in their place, according to the commandment of David, and Asaph, and Heman, and Jeduthun the king's seer; and the doorkeepers were at every gate; they had not to depart from their service, for their brethren the Levites prepared for them.

1 Chronicles 9:17-19

And the doorkeepers: Shallum, and Akkub, and Talmon, and Ahiman, and their brethren; Shallum was the chief.

1 Chronicles 25:1-7

And David and the captains of the host separated for the service those of the sons of Asaph and of Heman and of Jeduthun who were to prophesy with harps and lutes and cymbals; and the number of the men employed according to their service was:

1 Chronicles 26:12-19

Among these were the divisions of the doorkeepers, among the head-men, as to the charges together with their brethren, for performing the service in the house of Jehovah.

1 Chronicles 16:41-42

and with them Heman and Jeduthun, and the rest that were chosen, who were expressed by name, to give thanks to Jehovah, because his loving-kindness endureth for ever;

1 Chronicles 23:5

and four thousand were doorkeepers; and four thousand praised Jehovah with the instruments which I made, said David, to praise therewith.

2 Chronicles 29:25-26

And he set the Levites in the house of Jehovah with cymbals, with lutes, and with harps, according to the commandment of David, and of Gad the king's seer, and of Nathan the prophet; for the commandment was of Jehovah through his prophets.

Psalm 77:1

{To the chief Musician. On Jeduthun. Of Asaph. A Psalm.} My voice is unto God, and I will cry; my voice is unto God, and he will give ear unto me.

Psalm 78:1

{An instruction. Of Asaph.} Give ear, O my people, to my law; incline your ears to the words of my mouth.

Psalm 79:1

{A Psalm of Asaph.} O God, the nations are come into thine inheritance: thy holy temple have they defiled; they have laid Jerusalem in heaps.

Treasury of Scripture Knowledge

Summary

And the singers the sons of Asaph were in their place, according to the commandment of David, and Asaph, and Heman, and Jeduthun the king's seer; and the porters waited at every gate; they might not depart from their service; for their brethren the Levites prepared for them.

Bible References

The porters

1 Chronicles 9:17
And the doorkeepers: Shallum, and Akkub, and Talmon, and Ahiman, and their brethren; Shallum was the chief.
1 Chronicles 26:14
And the lot eastward fell to Shelemiah; and they cast lots for Zechariah his son, a wise counsellor, and his lot came out northward;