´It was narrated that Fatimah the daughter of the Messenger of Allah said:` "Whenever the Messenger of Allah entered the mosque he would say: 'Bismillah, was-salamu 'ala Rasulillah, Allahummagh-firli dhunubi waftah li abwaba rahmatika. (In the Name of Allah, and peace be upon the Messenger of Allah. O Allah, forgive me my sins and open to me the gates of Your mercy).' When he left he would say: 'Bismillah, was-salamu 'ala Rasulillah, Allahummagh-firli dhunubi waftah li abwaba fadlika. (In the Name of Allah, and peace be upon the Messenger of Allah. O Allah, forgive me my sins and open to me the gates of Your bounty).'"
Hadith Referenceسنن ابن ماجه / كتاب المساجد والجماعات / 771
Commentary: Our esteemed researcher has declared this narration weak in terms of its chain of transmission, and has further stated that the following narration suffices in its place. In addition, some scholars have declared this narration to be authentic.
Source: Commentary on Sunan Ibn Mājah by Mawlānā ‘Atā’ullāh Sājid, Page: 771
´Fatimah the Great narrated:` "When Allah's Messenger entered the Masjid he said Salat and Salam upon Muhammad and then said: (Rabbighfirli dhunubi, waftahli abwaba rahmatik) 'O pardon my sins, and open the gates of Your mercy for me.' And when he exited he said Salat and Salam upon Muhammad, and then said: (Rabbighfirli dunubi, waftahli abwaba rakmatik) 'O Lord pardon my sins, and open the gates of Your blessings for me.'"
Shaykh Dr. Abdur Rahman Freywai
Commentary: Note: (Fatima bint Husayn did not meet Fatima Kubra, but based on evidences, this hadith is authentic. Shaykh al-Albani says: Except for the sentence regarding forgiveness, the rest of the hadith is authentic, Taraaju‘ al-Albani: 510)
Source: Sunan al-Tirmidhi – Majlis ‘Ilmi Dar al-Da‘wah, New Delhi Edition, Page: 314