[1] Baydāʾ is a desert plain in the Hejaz, on the road between Mecca and Medina, but just south of the latter. It is to Mecca’s northeast, while Mecca is to Medina’s southwest. The army that the Earth will swallow there is one holding allegiance to the Sufyānī, sent by him to hunt Imam al-Mahdī عجل الله فرجه down and kill him at Mecca, having received news that he has fled Medina to go there. This is in Shaykh al-Nuʿmānī’s Kitāb al-Ghayba, in chapter 14—“The Signs Preceding the Reappearance,” in tradition no. 67, on page 289: ويبعث السفياني بعثاً إلى المدينة فينفر المهدي منها إلى مكة، فيبلغ أمير جيش السفياني أن المهدي قد خرج إلى مكة، فيبعث جيشاً على أثره فلا يدركه… The Sufyānī will send (an army) to Medina, whereupon the Mahdī will go forth from there towards Mecca. It will reach the commander of the Sufyānī’s troops that he (the Mahdī) has gone out towards Mecca, so he will send a contingent to track him down, but they will not find him.

[2] Al-Nafs al-Zakiyya (النفس الزكية)—“the Irreproachable Soul,” is the name by which the Mahdī’s envoy, a youth from the House of the Apostle of Allāh صلى الله عليه وعلى آله who will serve in the same capacity as Muslim b. ʿAqīl عليه السلام did for Imam al-Ḥusayn صلوات الله عليه, is known throughout the Mahdī-centric eschatological content across the whole of the Imāmī corpus of traditions (أحاديث). The following excerpt from a report in Shaykh al-Ṭāʾifa’s Kitāb al-Ghayba indicates that, like the Imam himself, al-Nafs al-Zakiyya’s real name is Muḥammad b. al-Ḥasan, as well as the nature of his demise at the hands of the Sufyānī’s people: عنه، عن محمد بن خلف الحداد[ي]، عن إسماعيل بن أبان الأزدي، عن سفيان بن إبراهيم الجريري أنه سمع أباه يقول: النفس الزكية غلام من آل محمد اسمه: محمد بن الحسن يقتل بلا جرم ولا ذنب، فإذا قتلوه لم يبق لهم في السماء عاذر ولا في الأرض ناصر. And from him (Qarqāra), from Muḥammad b. Khalaf al-Ḥaddād[i], from Ismāʿīl b. Abān al-Azdī, from Sufyān b. Ibrāhīm al-Jarīrī, that he heard his father saying: “The Irreproachable Soul is a young man from the House of Muḥammad, whose name is Muḥammad b. al-Ḥasan. He will be murdered without having committed any crime or sin, and once they have murdered him, they will find none to present an excuse for them in heaven, nor a supporter upon the face of the Earth.” Shaykh al-Ṭāʾifa, Kitāb al-Ghayba, chapter 51: “Signs Preceding the Reappearance of Imam al-Mahdī عليه السلام,” tradition no. 59/480, p. 464.