Chapter on the Manner of Prayer, Explanation of the Fifty-One Rak‘ahs; The Order, Recitation, Tasbih in Bowing and Prostration, Qunut, and What is Obligatory and Recommended Therein

And from him, from Ali ibn Muhammad, from Sahl ibn Ziyad, from Ali ibn Mahziyar, who said: I (Ali ibn Mahziyar) read in the letter of a man to Abu Ja‘far عليه السلام, peace be upon him, asking: "The two rak‘ahs before the Fajr prayer, are they from the night prayer or from the day prayer? And at what time should I perform them?" So He عليه السلام wrote in his own handwriting: "Insert them into the night prayer as an insertion."