Musnad Abu Ya'la al-Mawsili 117:81

'Abd al-Rahman narrated to us, Hammad narrated to us, from Thabit, from Anas, that 'Ubayd Allah ibn Ziyad said: "O Abu Hamzah, did you hear the Prophet, may Allah bless him and grant him peace, mention the Hawd (the Cistern)?" He said: "I have left behind in Medina old women who frequently ask Allah to bring them to the Hawd of Muhammad, may Allah bless him and grant him peace."