Sunan Abi Dawud Book 2, Hadith 129
Urwah ibn az-Zubayr reported on the authority of a woman from Banu an-Najjar. She said: My house was the loftiest of all the houses around the mosque (of the Prophet at Medina). Bilal used to make a call to the morning prayer from it. He would come there before the break of dawn and wait for it. When he saw it, he would yawn and say: O Allah, I praise you and seek Your assistance for the Quraysh so that they might establish Thine religion. He then would make the call to prayer.
She (the narrator) said: By Allah, I do not know whether he ever left saying these words on any night.
This tradition has also been transmitted through a different chain of narrators by Abu Hurairah who reported it in a similar manner from the Messenger of Allah (ﷺ).
I came to the prophet (ﷺ) at Mecca; he was sitting in a tent made of leather. Then Bilal came out and called to prayer. I looked at his mouth following him this side and that side (i.e., right and left). Later at his Messenger of Allah (ﷺ) came out clad in a red suit, i.e, wearing the sheets of the Yemen, of the Qatri design. The version narrated by Musa has the word; “I saw Bilal going towards al-Abtah”.
He then made a call to prayer. When he reached the words “ come to prayer, come to salvation”. He turned his neck right and left, respectively; he did not turn himself (with his whole body). He then entered (his house) and came out with a lancet. The narrator then reported the rest of the tradition.