2 Chronicles 35:15

And the singers, the sons of Asaph were in their place, according to the command of David, and Asaph, and Heman, and Jeduthun, the king's seer. And the gatekeepers were at every gate. It was not for them to depart from their service; for their brothers the Levites prepared for them.

1 Chronicles 9:17-19

And the gatekeepers were Shallum, and Akkub, and Talmon, and Ahiman; and their brothers, Shallum was the chief.

1 Chronicles 25:1-7

And David and the army commanders separated to the service those of the sons of Asaph, and of Heman, and of Jeduthun, who were prophets with lyres and with cymbals. And the number of the workmen according to their service was:

1 Chronicles 26:12-19

Among these were the divisions of the gatekeepers, among the chief men, having charges like their brothers, to minister in the house of Jehovah.

1 Chronicles 16:41-42

And he left with them Heman and Jeduthun, and the rest who were chosen, who were called by name, to give thanks to Jehovah, because His mercy endures forever.

1 Chronicles 23:5

And four thousand were gatekeepers, and four thousand praised Jehovah with the instruments which David made for praising.

2 Chronicles 29:25-26

And he set the Levites in the house of Jehovah with cymbals, with harps, and with lyres, according to the command of David, and of Gad the king's seer and Nathan the prophet. For the commandment was by the hand of Jehovah by His prophets.

Psalm 77:1

To the Chief Musician. To Jeduthun. A Psalm of Asaph. I cried to God with my voice, to God is my voice; and He gave ear to me.

Psalm 78:1

An instruction of Asaph. Give ear, O my people, to my law; bow down your ears to the words of my mouth.

Psalm 79:1

A Psalm of Asaph. O God, the nations have come into Your inheritance; they have defiled Your holy temple; 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 gatekeepers were Shallum, and Akkub, and Talmon, and Ahiman; and their brothers, Shallum was the chief.
1 Chronicles 26:14
And the lot eastward fell to Shelemiah; then Zechariah his son, a wise counselor, they cast lots. And his lot came out northward.