Sahih al-Bukhari Book 61, Hadith 124
There was a Christian who embraced Islam and read Surat-al-Baqara and Al-`Imran, and he used to
write (the revelations) for the Prophet. Later on he returned to Christianity again and he used to say:
"Muhammad knows nothing but what I have written for him." Then Allah caused him to die, and the
people buried him, but in the morning they saw that the earth had thrown his body out. They said,
"This is the act of Muhammad and his companions. They dug the grave of our companion and took his
body out of it because he had run away from them." They again dug the grave deeply for him, but in
the morning they again saw that the earth had thrown his body out. They said, "This is an act of
Muhammad and his companions. They dug the grave of our companion and threw his body outside it,
for he had run away from them." They dug the grave for him as deep as they could, but in the morning
they again saw that the earth had thrown his body out. So they believed that what had befallen him
was not done by human beings and had to leave him thrown (on the ground).
The Prophet (ﷺ) paid a visit to a sick bedouin. The Prophet (ﷺ) when visiting a patient used to say, "No harm will befall you! May Allah cure you! May Allah cure you!" So the Prophet (ﷺ) said to the bedouin. "No harm will befall you. May Allah cure you!" The bedouin said, "You say, may Allah cure me? No, for it is a fever which boils in (the body of) an old man, and will lead him to the grave." The Prophet (ﷺ) said, "Yes, then may it be as you say."
Allah's Messenger (ﷺ) said, "When Khosrau perishes, there will be no (more) Khosrau after him, and when Caesar perishes, there will be no more Caesar after him. By Him in Whose Hands Muhammad's life is, you will spend the treasures of both of them in Allah's Cause."