Hadith 871
´It was narrated that ‘Ali bin Shaiban who was part of a delegation (to the Prophet (ﷺ)) said:` “We set out until we came to the Messenger of Allah (ﷺ), and we gave him our oath of allegiance and performed prayer behind him. He glanced out of the corner of his eye at a man who was not settling his spine when he bowed and prostrated. When the Prophet (ﷺ) finished the prayer, he said: ‘O Muslims, there is no prayer for the one who does not settle his spine when bowing and prostrating.’”
Hadith 1003
´‘Abdur-Rahman bin ‘Ali bin Shaiban narrated that his father, ‘Ali bin Shaiban, who was part of the delegation, said:` “We set out until we came to the Prophet (ﷺ). We gave him our oath of allegiance and performed prayer behind him. Then we offered another prayer behind him. He finished the prayer and saw a man on his own, praying behind the row.” He said: “The Prophet of Allah (ﷺ) stood beside him and when he finished he said: ‘Repeat your prayer; there is no prayer for the one who is behind the row.’”