Sahih Bukhari Volume 004, Book 055, Hadith Number 605.
Narated By 'Aisha : The Prophet returned to Khadija while his heart was beating rapidly. She took him to Waraqa bin Naufal who was a Christian convert and used to read the Gospels in Arabic Waraqa asked (the Prophet), "What do you see?" When he told him, Waraqa said, "That is the same angel whom Allah sent to the Prophet) Moses. Should I live till you receive the Divine Message, I will support you strongly."