Abu Humayd and Abu Usaid Ansari (may Allah be pleased with them) say that the Messenger of Allah (peace and blessings be upon him) said: "When any one of you enters the mosque, he should first send peace and blessings upon the Prophet (peace be upon him), then say: «اَللّٰهُمَّ افْتَحْ لِيْ أَبْوَابَ رَحْمَتِكَ» 'O Allah, open the doors of Your mercy for me.' And when he leaves the mosque, he should say: «اَللّٰهُمَّ إِنِّيْ أَسْأَلُكَ مِنْ فَضْلِكَ» 'O Allah, I ask You for Your bounty,' meaning sustenance and other worldly blessings."