The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness
حَدَّثَنَا يَحْيَى بْنُ يَحْيَى، وَقُتَيْبَةُ بْنُ سَعِيدٍ، وَأَبُو الرَّبِيعِ الْعَتَكِيُّ، جَمِيعًا عَنْ حَمَّادٍ، قَالَ يَحْيَى أَخْبَرَنَا حَمَّادُ بْنُ زَيْدٍ، عَنْ ثَابِتٍ، عَنْ أَبِي بُرْدَةَ، عَنِ الأَغَرِّ الْمُزَنِيِّ، - وَكَانَتْ لَهُ صُحْبَةٌ - أَنَّ رَسُولَ اللَّهِ صلى الله عليه وسلم قَالَ " إِنَّهُ لَيُغَانُ عَلَى قَلْبِي وَإِنِّي لأَسْتَغْفِرُ اللَّهَ فِي الْيَوْمِ مِائَةَ مَرَّةٍ " .Al-Agharr al-Muzani, who was one amongst the Companions (of the Holy Prophet) reported that Allah's Messenger (ﷺ) said:There is (at times) some sort of shade upon my heart, and I seek forgiveness from Allah a hundred times a day
From Sahih Muslim, whose reports the scholars accept as authentic.