Sahih Bukhari
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
Volume: 005 / Book Number: 059 / Hadith Number: 719
Narrated 'Aisha:
Used to hear (from the Prophet) that no Prophet dies till he is given the option to select either the worldly life or the life of the Hereafter. I heard the Prophet in his fatal disease, with his voice becoming hoarse, saying, "In the company of those on whom is the grace of Allah ..( to the end of the Verse )." (4.69) Thereupon I thought that the Prophet had been given the option.