Silsilat al-Ahadith al-Sahihah

Lady Aisha (may Allah be pleased with her) says: The Messenger of Allah (peace and blessings be upon him) went out of the house one night, so I sent Barirah after him so that she could see where he was going. She came back and informed me that the Prophet (peace and blessings be upon him) had gone towards Baqi' al-Gharqad (a cemetery), stood in the lower part of Baqi', then raised his hands (in supplication) and returned. In the morning, I myself asked the Prophet (peace and blessings be upon him): Where did you go last night? He (peace and blessings be upon him) replied: "I was sent to pray for mercy for the people of Baqi' cemetery."