From him, from Muhammad ibn Isa from Al-Husayn ibn Ali ibn Yaqtin from Muhammad ibn Al-Fudayl Al-Kufi from Sa‘d ibn Abi ‘Amr al-Jallab, who said: I said to Abu Abdillah عليه السلام: “The two units of the Fajr prayer (the supererogatory rak‘ahs before the obligatory Fajr), if I miss them, should I make them up?” Imam عليه السلام said: “Yes.” I said: “Why? Are they obligatory?” Imam عليه السلام said: “The Messenger of Allah سبحانه وتعالى, may Allah سبحانه وتعالى bless him and his family, established them as a Sunnah. And whatever the Messenger of Allah سبحانه وتعالى, may Allah سبحانه وتعالى bless him and his family, establishes as a Sunnah is an obligation.”