Hadith 31:24
Sahih (Al-Albani)
Ibn 'Umar said, "I heard the Prophet, may Allah bless him and grant him peace, asking Allah to forgive him a hundred times in this assembly with the words, 'O Allah, forgive me and turn to me and show mercy to me. You are the Ever-Turning back (to his slaves), Merciful.'"
حَدَّثَنَا جَنْدَلُ بْنُ وَالِقٍ، قَالَ: حَدَّثَنَا يَحْيَى بْنُ يَعْلَى، عَنْ يُونُسَ بْنِ خَبَّابٍ، عَنْ مُجَاهِدٍ، عَنِ ابْنِ عُمَرَ قَالَ: سَمِعْتُ النَّبِيَّ صلى الله عليه وسلم يَسْتَغْفِرُ اللَّهَ فِي الْمَجْلِسِ مِئَةَ مَرَّةٍ: رَبِّ اغْفِرْ لِي، وَتُبْ عَلَيَّ، وَارْحَمْنِي، إِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيمُ
Original Reference: Al-Adab Al-Mufrad 627