Sayyidah Fatimah (may Allah be pleased with her) said that when the Messenger of Allah (peace and blessings be upon him) entered the mosque, he would send blessings upon the Prophet (peace and blessings be upon him) and say: "O Allah, forgive me my sins and open for me the doors of Your mercy." And when he went out, he would send blessings upon the Prophet (peace and blessings be upon him) and say: "O Allah, forgive me my sins and open for me the doors of Your bounty."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 19247