Sayyiduna Ali bin Shiban (may Allah be pleased with him) narrates that the Messenger of Allah (peace and blessings be upon him) saw a man praying alone behind the row. So the Messenger of Allah (peace and blessings be upon him) waited until that person finished his prayer. Then the Messenger of Allah (peace and blessings be upon him) said: "Repeat your prayer, for there is no prayer for the one who prays alone behind the row."