At a sitting or gathering

Ibn Umar (ra) said: Allah's Messenger (ﷺ) used to repeat in a single sitting: Rabbigh’fir lī wa tub `alayy innaka antat-Tawwābu ‘l-Ghafūr.

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.

[ Sahih Ibn Majah 2/321. See also Al-Albani, Sahih At-Tirmidhi 3/153. Hisn al-Muslim 195 ]