From Ibn Umar-RadiAllaahu anhumma – who said:
“We would count that the Messenger of Allaah –sallAllaahu alayhi wa sallam- would say in one sitting one hundred times:
رَبِّ اغْفِرْليِ وَتُبْ عَلَيَّ إِنَّكَ أَنْتَ التَّوَّابُ الرَّحِيمُ
“O my Lord forgive me and accept my repentance indeed You are the One who forgives and Most Merciful.”
Rab-bigh-firlee wa tubb alayya Innaka anta
at-Tawaabu ar-Raheem.
[Collected by Abu Dawood, Tirmidhi &
authenticated by Albaani in Saheeh Abi
Dawood 5/248]
Translation source: Miraath Publications