Sunan Ibn Majah

It was narrated that Abu Humaid As-Sa'idi said:""The Messenger of Allah said: 'When anyone of you enters the mosque, let him send peace upon the prophet, then let him say: ""Allahummaftah li abwaba rahmatika (O Allah, open to me the gates of Your mercy)."" And when he leaves, let him say: ""Allahumma inni as'aluka min fadlika. (O Allah, I ask of you from Your bounty)