Bilal used to give the call to prayer once the sun had passed its zenith, but he would not begin the iqamah until the Prophet ﷺ came out. When the Prophet ﷺ appeared, Bilal would call the iqamah as soon as he saw him.
كان بلال يؤذن إذا دحضت، فلا يقيم حتى يخرج النبي ﷺ، فإذا خرج أقام الصلاة حين يراه.
Muslim narrated it in the Book of Mosques (606), from Salama bin Shabib, who said, Hasan bin Ayn narrated to us, who said, Zuhayr narrated to us, who said, Simak bin Harb narrated to us, from Jabir bin Abdullah, and he related the hadith.Abu Dawud (537) and Tirmidhi (202) also narrated it, via Israil, from Simak bin Harb, and in it, "The muezzin of the Messenger of Allah ﷺ would give the adhan, then wait a while, and when he saw the Prophet ﷺ come out, he would give the call to start the prayer." Tirmidhi did not name the muezzin, but Abu Dawud named him as Bilal.Tirmidhi said, "This is what some scholars have said, 'The muezzin has more right over the adhan, and the imam has more right over the call to start the prayer.'"I say, Tirmidhi's statement is correct. As for what is narrated from Abu Hurairah as a marfu report, "The muezzin has more right over the adhan, and the imam has more right over the call to start the prayer. O Allah, guide the imams rightly and forgive the muezzins," it is daif. Ibn Adi narrated it in Kamil (4/1327), from Muhammad bin Ishaq bin Ibrahim bin Faruq, who said, Ali bin Ashkab narrated to us, who said, Yahya bin Ishaq narrated to us, who said, Sharik narrated to us, from Amash, from Abu Salih, from Abu Hurairah, and he related the hadith.Ibn Adi said, "This wording is only narrated from Sharik, through the narration of Yahya bin Ishaq from him. Others narrated it from Amash with different wording, namely, 'The imam is a guarantor and the muezzin is trusted. O Allah, guide the imams rightly and forgive the muezzins.'" The hadith of Amash has already been referenced earlier.Bayhaqi narrated it in Kubra (19/2) as words of Ali bin Abu Talib, and said, "It was also narrated from Sharik, from Amash, from Abu Salih, from Abu Hurairah, as a marfu report, but it is not preserved."His statement, "So when he came out, he would give the call to start the prayer as soon as he saw him," does not contradict what is established in Sahihayn, Bukhari in the Book of Supplications (6310) and Muslim in the Book of the Prayer of the Traveler (736), "When Fajr broke, the Messenger of Allah ﷺ would pray two light rakahs, then lie down on his right side until the muezzin came to him and called the adhan to him." In Muslim's version, "until the muezzin came to him for the call to start the prayer."So the meaning of this is that Bilal used to watch for the Messenger of Allah ﷺ to come out. When he saw him, he would begin the call to start the prayer before the people saw him. Sometimes, if the Prophet ﷺ was late in coming out, he would go to his door to check on him, and to let him know that the time had come, so that when he came out, he would begin the call to start the prayer.