4. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad from al-Husayn ibn Sa‘id from Fadalah ibn Ayyub from abu al- Mighra’ from abu Basir who has said the following
“Abu ‘Abd Allah (a.s.), has said that ’Amir al-Mu’minin has said, ‘One who does not straighten his back during Salah (prayer), his Salah (prayer) is not valid.’”