Malik b. al-Huwairith said that he and a cousin of his came to the Prophet, who said, “When you two are on a journey, you should call the adhan and repeat the iqama, then the older of you should act as imam.”
Samura b. Jundub reported God’s Messenger as saying, “Do not let Bilal’s adhan or the false dawn prevent you from taking your morning meal , but only the dawn which is widely spread in the horizon.”
Muslim transmitted it, but the wording is Tirmidhi’s.
He also told of God's Messenger saying to them, “Pray as you have seen me prayer, and when the time for prayer comes one of you should call the adhan for you and the oldest of you should act as imam.”*
* In this tradition the plural is used throughout; in the preceding the dual is used, two persons being referred to.
Ibn ‘Umar reported God’s Messenger as saying, “Bilal summons to prayer when it is still night, so eat and drink till Ibn Umm Maktum makes the summons.” He added that Ibn Umm Maktum was a blind man who did not make the summons till someone said to him, “The morning has come, the morning has come.”