1 Chronicles 25:3

“Afterward you will come to the hill of God where the Philistine garrison is; and it shall be as soon as you have come there to the city, that you will meet a group of prophets coming down from the high place with harp, tambourine, flute, and a lyre before them, and they will be prophesying.

And with them were Heman and Jeduthun, and the rest who were chosen, who were designated by name, to give thanks to Yahweh, because His lovingkindness endures forever.

and all the Levitical singers, Asaph, Heman, Jeduthun, and their sons and relatives, clothed in fine linen, with cymbals, harps, and lyres, standing east of the altar, and with them 120 priests blowing trumpets

From the outside to the inner gate were chambers for the singers in the inner court, one of which was at the side of the north gate, with its front toward the south, and one at the side of the south gate facing toward the north.