When the holy prophet (peace be upon him) died, muslims were in a great shock, disbelief and huge sorrow. Some refused to believe that he was dead. Umar bin Khattab, one of the blessed 10 companions and the second caliph for muslims said "If anyone says that the Messenger of Allâh is dead, I will cut off his head". As per him he had gone to God like Moses (peace be upon him) did and this was just a test for the muslims.
However one of the companions of the prophet came forward and recited this from QURAN;
"Muhammad is only a Messenger of Allâh, there have been Messengers before him. What then, will you turn back from Islâm if he dies or is killed?".
Then the same companion said: "O People! If anyone among you worshipped Muhammad, let him know that Muhammad is dead. But those who worshipped Allâh, let them know that He lives and will never die.
Then theses words started sinking among muslims and they realised their most loved prophet, who was their life, who they would obey no matter what he said, was not going to be arround them anymore. Can anyone name the companion who reduced the confusion among muslims when the holy prophet Muhammed (peace be upon him) died.
Originally posted by Sarai: I had to cheat by Googling it, but I found it! Abu Bakr!
That is right & Abu Bakr (may Allah be pleased with him) was the 4th person to accept islam & became the first caliph for muslims. One can perhaps call him as the best friend of prophet Muhammed (peace be upon him). He remained with the holy prophet throughout his life time, and hardly ever questioned any action of the holy prophet.