Malik related to me from AIqama ibn Abi Alqama that his mothersaid that she had heard A'isha, the wife of the Prophet, may Allahbless him and grant him peace, say, "The Messenger of Allah, may Allahbless him and grant him peace, rose one night and put on his clothesand then went out. I ordered my slave-girl, Barira, to follow him, andshe followed him until he got to al-Baqi. He stood near it as long asAllah willed and then he left. Barira arrived back before him and toldme and I did not say anything to him until morning, and then Imentioned it to him and he explained, 'I was sent out to the people ofal-Baqi to pray for them.' "
USC-MSA web (English) reference: Book 16, Hadith 57
Arabic reference: Book 16, Hadith 579