Chapter on Rulings on Forgetfulness (Sahw) in Prayer and What Requires Repeating of Prayer

And Sa‘d narrated from Muhammad bin al-Husayn, from Ja‘far bin Bashir, from al-Harith bin al-Mughirah al-Nasri, who said: I said to Abu Abdillah عليه السلام, peace be upon him: “We prayed Maghrib, and the imam (of prayer) was forgetful and performed the taslim after two rak‘ahs, so we repeated the prayer.” Imam عليه السلام said: "And why did you repeat it? Did not the Messenger of Allah سبحانه وتعالى (peace be upon him and his family) once leave the prayer after two rak‘ahs and then complete it with two more (rak’ahs)? Should you not have completed it?"