Sahih Bukhari Volume 2, Book 23, Hadith Number 333.

Narated By ‘Aisha  : Abu Bakr came riding his horse from his dwelling place in As-Sunh. He got down from it, entered the Mosque and did not speak with anybody till he came to me and went direct to the Prophet, who was covered with a marked blanket. Abu Bakr uncovered his face. He knelt down and kissed him and then started weeping and said, “My father and my mother be sacrificed for you, O Allah’s Prophet! Allah will not combine two deaths on you. You have died the death which was written for you.”

Narrated Abu Salama from Ibn Abbas : Abu Bakr came out and ‘Umar , was addressing the people, and Abu Bakr told him to sit down but ‘Umar refused. Abu Bakr again told him to sit down but ‘Umar again refused. Then Abu Bakr recited the Tashah-hud (i.e. none has the right to be worshipped but Allah and Muhammad is Allah’s Apostle) and the people attended to Abu Bakr and left ‘Umar. Abu Bakr said, “Amma ba’du, whoever amongst you worshipped Muhammad, then Muhammad is dead, but whoever worshipped Allah, Allah is alive and will never die. Allah said: ‘Muhammad is no more than an Apostle and indeed (many) Apostles have passed away before him… (up to the) grateful.’ ” (3.144) (The narrator added, “By Allah, it was as if the people never knew that Allah had revealed this verse before till Abu Bakr recited it and then whoever heard it, started reciting it.”)