Call to Prayers : Adhaan History

Narrated Ibn 'Umar:

When the Muslims arrived at Medina, they used to assemble for the prayer, and used to guess the time for it. During those days, the practice of Adhan for the prayers had not been introduced yet. Once they discussed this problem regarding the call for prayer. Some people suggested the use of a bell like the Christians, others proposed a trumpet like the horn used by the Jews, but 'Umar was the first to suggest that a man should call (the people) for the prayer; so Allah's Apostle ordered Bilal to get up and pronounce the Adhan for prayers.

Bukhari :: Book 1 :: Volume 11 :: Hadith 578

Muhammad SAW About Prophet David

Narrated Abdullah bin 'Amr bin Al-'As:

Allah's Apostle told me, "The most beloved prayer to Allah is that of David and the most beloved fasts to Allah are those of David. He used to sleep for half of the night and then pray for one third of the night and again sleep for its sixth part and used to fast on alternate days."