Musnad Ahmad 8:73

Hajjaj narrated to us, Fatar narrated to us, from Abdullah ibn Sharik, from Abdullah ibn al-Ruqaym al-Kinani, who said: We went out to Medina during the time of the Battle of the Camel, and we met Sa’d ibn Malik there. He said: "The Messenger of Allah, peace and blessings of Allah be upon him, ordered the closing of the doors that opened into the mosque, and he left the door of Ali, may Allah be pleased with him."