Narrated Anas:
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… Volume 4, Book 56, Number 814: (Bukhari Translation
Muhsin Khan.)