At a sitting or gathering1 du'a

Ibn Umar (ra) said: Allah's Messenger (ﷺ) used to repeat in a single sitting: My Lord, forgive me, a...

Reference:Sahih Ibn Majah 2/321. See also Al-Albani, Sahih At-Tirmidhi 3/153.Hisnul Muslim 195

عن ابن عمر قال : كان يعد لرسول الله صلى الله عليه وسلم في المجلس الواحد مائة مرة من قبل أن يقوم 'رب اغفر لي وتب علي إنك أنت التواب الغفور

Transliteration

Rabbigh’fir līwa tub `alayyinnaka antat-Tawwābu ‘l-Ghafūr.

Translation

Ibn Umar (ra) said: Allah's Messenger (ﷺ) used to repeat in a single sitting: My Lord, forgive me, and accept my repentance, You are the Ever-Relenting, the All-Forgiving.