abu bakr left his house at as-sunh and came forth to the mosque on a mare-back. at the mosque, he dismounted and entered. he talked to nobody but went on till he entered ‘aishah’s abode, and went directly to where the messenger of allâh [pbuh] was. the prophet [pbuh] was covered with a yemeni mantle. he uncovered his face and tended down, kissed him and cried. then he said: "i sacrifice my father and mother for your sake. allâh, verily, will not cause you to die twice. you have just experienced the death that allâh had ordained."
then he went out and found ‘umar talking to people. he said: "‘umar, be seated." ‘umar refused to do so. people parted ‘umar and came towards abu bakr, who started a speech saying:
"and now, he who worships muhammad [pbuh]. muhammad is dead now. but he who worships allâh, he is ever living and he never dies. allâh says:
‘muhammad ([pbuh])is no more than a messenger, and indeed (many) messengers have passed away before him. if he dies or is killed, will you then turn back on your heels (as disbelievers)? and he who turns back on his heels, not the least harm will he do to allâh, and allâh will give reward to those who are grateful.’" [al-qur'an 3:144]
ibn ‘abbas said: "by allâh, it sounded as if people had never heard such a qur’ânic verse till abu bakr recited it as a reminder. so people started reciting it till there was no man who did not recite it."
ibn al-musaiyab said that ‘umar had said: "by allâh, as soon as i heard abu bakr say it, i fell down to the ground. i felt as if my legs had been unable to carry me so i collapsed when i heard him say it. only then did i realize that muhammad [pbuh] had really died." [sahih al-bukhari 2/640,641]