((عَنِ ابْنِ عُمَرَ رضي الله عنه قَاَلَ: كَانَ يُعَدُّ لِرَسُولِ اللَّهِ صلى الله عليه وسلم فِي الْمَجْلِسِ الوَاحِدِ مِائَةُ مَرَّةٍ مِنْ قَبْلِ أَنْ يَقُومَ: ((رَبِّ اغْفِرْ لِي، وَتُبْ عَلَيَّ، إِنَّكَ أَنْتَ التَّوَّابُ الغَفُورُ)).
(Ibn AAumar said: It would be counted that the Messenger of Allah would say one hundred times at any one sitting before getting up: (O my Lord, forgive me and turn towards me (to accept my repentance). Verily You are The Oft-Returning. The Oft-Forgiving.))
Sahih Ibn Majah 2/321. See also Al-Albani, Sahih At-Tirmidhi 3/153.