“The city of Al-Madeenah literally trembled on the day that Abu Bakr (radi Allaahu ‘anhu) died; in fact; other than the day of the Prophet’s death the people of Madeenah had never witnessed a sadder day, nor a day upon which they had shed more tears. Upon hearing the sad news, ‘Ali ibn Abi-Talib (radi Allaahu ‘anhu) hurried towards Abu Bakr’s house, all the while saying, “Verily we belong to Allah, and to Him is our return.”
‘Ali (radi Allaahu ‘anhu) then stood outside the house in which Abu Bakr (raadi Allaahu ‘anhu) had died, and made the following long speech, which he addressed to Abu Bakr (raadi Allaahu ‘anhu) himself:
“O Abu Bakr, may Allah have Mercy upon you. You were the closest companion and friend of the Messenger of Allah (salAllaahu ‘alayhi wa sallam); you were a comfort to him; you were the one he trusted most. If he had a secret, he would tell it to you; and if he needed to consult someone regarding a matter, he would consult you. You were the first of your people to embrace Islam, and you were the most sincere of them in your faith. Your faith was stronger than any other person’s, as was the degree to which you feared Allah. And you were wealthier then anyone else in terms of what you acquired from the religion of Allah ‘Azza Wa-Jall (The Posessor of Might and Majesty). You cared most for both the Messenger of Allah (salAllaahu ‘alayhi wa sallam) and Islam. Of all people, you were the best Companion to the Messenger of Allah (salAllaahu ‘alayhi wa sallam); you possessed the best qualities; you had the best past; you ranked the highest; and you were closest to him. And of all people you resembled the Messenger of Allah (salAllaahu ‘alayhi wa sallam) the most in terms of his guidance and demeanor. Your ranking was higher than anyone else’s, and the Prophet (salAllaahu ‘alayhi wa sallam) honored you and held you in higher esteem than anyone else. On behalf of the Messenger of Allah and Islam, may Allah reward you with the best of rewards. When the people disbelieved in the Messenger of Allah (salAllaahu ‘alayhi wa sallam) you believed in him. Throughout his life, you were both his eyes with which he (salAllaahu ‘alayhi wa sallam), and his ears with which he heard. Allah has named you truthful in his book when He said:
“And he (Muhammad (salAllaahu ‘alayhi wa sallam) who has brought the truth (this Qur’an and Islamic Monotheism) and (those who) believed therein (i.e. the true believers of Islamic Monotheism), those are Al-Muttaqun (the pious and righteous persons)” (Qur’an 39:33)
When people were stingy in their support for the Messenger of Allah (salAllaahu ‘alayhi wa sallam) you comforted him. And when people sat still, you stood side by side with the Messenger of Allah (salAllaahu ‘alayhi wa sallam), facing the same hardships that he faced. In times of hardship, you were truly a good and noble Companion of his. You were the ‘second of two’, his Companion in the Cave; and the one upon whom As-Sakeenah descended. You were his Companion during the migration and you were his successor regarding the religion of Allah and His nation. And truly good sucessor you proved to be when the people apostatized.
You did what no other Khaleefah of a Prophet did before you. You stood up firmly and bravely when his other Companions lost their resolve and became soft. And when they became weak, you adhered to the methodology of the Messenger of Allah (salAllaahu ‘alayhi wa sallam). You truly were as the Messenger of Allah (salAllaahu ‘alayhi wa sallam) said: weak in your body, but strong regarding the commands of Allah; humble in yourself, but lofty in your ranking with Allah; well-esteemed in the eyes of people, honored and great in their hearts. Not a single one of them had any reason to dislike you, to be suspicious of you, or to hold you in contempt.
The weak and humble you have always treated as strong and honorable, making sure you gave them what was rightfully theirs. And in this regard, you have treated relatives and strangers equally. Of all people, you respect those who are most obedient to Allah and who fear Him the most. In your overall character, you embody truth and compassion. Your speech has always been characterized by the qualities of wisdom and decisiveness. And you have always struck a noble balance between gentleness and firmness. You have always based your decisions on knowedge, and once you have made your decisions, you have always kept a firm resolve to execute them.
Verily to Allah do we belong, and to Him is our return. We are pleased with, and we submit to, Allah’s decree. And by Allah, other than the death of the Messenger of Allah (salAllaahu ‘alayhi wa sallam) Muslims have never been afflicted with a greater calamity than the calamity of your death. You have always been a protector, a sanctuary, and source of honor for this religion. May Allah ‘Azza Wa-Jall make you join the company of His Prophet, Muhammad (salAllaahu ‘alayhi wa sallam) and may He not deprive us of your reward. And may He not lead us astray after you.”
People had gathered around ‘Ali (raadi Allaahu ‘anhu) and listened to his speech until he was finished. Then they all cried with raised voices, and they all responded in unison to ‘Ali’s speech, saying, “Indeed, you have spoken the truth.” 
At-Tabsirah, by ibn Al-Jawzee (1/477-479); and Ashaab Ar-Rasool (1/108)