Sunan Ibn Majah 3814
سنن ابن ماجه#3814SahihIt was narrated that Ibn `Umar said:"We used to count that the Messenger of Allah (ﷺ) said one hundred times in a gathering: 'Rabbighfirli wa tub `alayya innaka Antat-Tawwabur-Rahim (O Allah forgive me and accept my repentance, for You are the Accepter of repentance, the Most Merciful)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Fouad Abd al-BaqiSahih
Shuaib Al ArnautSahih
Zubair Ali ZaiSahih
In-book reference: 33:158