Sayyiduna Ali bin Shiban (may Allah be pleased with him), who was included in the delegation that came to the service of the Prophet Muhammad (peace be upon him) from Banu Hanifa, narrates: I performed prayer behind the Prophet Muhammad (peace be upon him). When the Prophet Muhammad (peace be upon him) completed the prayer, he saw a man who was standing alone behind the row and performing prayer. The Prophet Muhammad (peace be upon him) asked him: Did you pray like this? He replied: Yes. The Prophet Muhammad (peace be upon him) said: Repeat your prayer, for the prayer of the one who stands alone behind the row is not valid.