SHAFAQNA – Imam Ali (AS) said: The Prophet of Islam (PBUH) used to reveal a new sign of good behaviour for me every day, and commanded me to follow him. The Prophet (PBUH) used to spend a few months of the year in the Cave of Hira, I was the only person to watch him, and no one else could see him. In those days, Islam had not entered any house except the house of the Prophet of Allah (SWT) where Lady Khadijah (AS) was also there, and I was the third person among them. I could see the light of revelation and the prophethood, and could smell the prophethood .
 Nahjul Balaghah, Sermon 192.