Sahih Muslim | Book 35 | Hadith Number 6522

Narrated by Al-Agharr al-Muzani
Al-Agharr al-Muzani, who was one amongst the Companions (of the Holy Prophet) reported that Allah's Messenger (may peace be upon him) said: There is (at times) some sort of shade upon my heart, and I seek forgiveness from Allah a hundred times a day.