"When Messenger of Allah 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.'"  

كَانَ رَسُولُ اللَّهِ ﷺ إِذَا دَخَلَ الْمَسْجِدَ صَلَّى عَلَى مُحَمَّدٍ وَسَلَّمَ وَقَالَ رَبِّ اغْفِرْ لِي ذُنُوبِي وَافْتَحْ لِي أَبْوَابَ رَحْمَتِكَ وَإِذَا خَرَجَ صَلَّى عَلَى مُحَمَّدٍ وَسَلَّمَ وَقَالَ رَبِّ اغْفِرْ لِي ذُنُوبِي وَافْتَحْ لِي أَبْوَابَ فَضْلِكَ  

"I met Abdullah bin al Husain in Makkah, so I asked him about this Hadith, so he narrated it to me, he said: 'When Messenger of Allah entered, he said (Rabbi aftahli abwaba rahmatik) 'O Lord, open the gates of Your mercy for me.' And when he exited he said: (Rabbi iftahli abwaba fadlik) 'O Lord, open the gates of Your blessings for me.'"  

رَبِّ افْتَحْ لِي بَابَ رَحْمَتِكَ وَإِذَا خَرَجَ $$قَالَ رَبِّ افْتَحْ لِي بَابَ فَضْلِكَ