Al-Bayhaqī then said:

Al-Ḥākim narrated to us; al-Aṣamm narrated to us; Aḥmad ibn ʿAbd al-Jabbār narrated to us; Abū Muʿāwiyah narrated to us, from al-Aʿmash, from Ismāʿīl ibn Rajāʾ, from his father, from Abū Saʿīd al-Khudrī, who said:
“I heard the Messenger of Allah ﷺ say, ‘Someone among you will fight for the Qurʾān’s interpretation just as I have fought for its revelation.’ Abū Bakr said, ‘Messenger of Allah, am I that man?’ He replied, ‘No.’ ʿUmar said, ‘Messenger of Allah, is it I?’ He replied, ‘No; rather, it is the one who mends the sandal’—meaning ʿAlī.”¹

Yaʿqūb ibn Sufyān said—through ʿUbayd Allāh ibn Muʿādh, from his father, from ʿImrān ibn Jarīr, from Lāḥiq:
“Those who revolted against ʿAlī at Nahrawān numbered four thousand men in armor. The Muslims charged them and slew them all, and only nine men from the Muslims were killed. If you wish, go to Abū Barzah, for he will testify to that.”

I say: The reports about fighting the Kharijites are mass-transmitted from the Messenger of Allah ﷺ, for they come by chains that yield certainty in the judgment of the scholars of this discipline. That the battle occurred in ʿAlī’s time is known by necessity to all people of knowledge. As for the circumstances of their emergence, its causes, Ibn ʿAbbās’s debate with them, and the fact that many of them returned, all of that will be detailed in its proper place, Allah Most High willing.

His ﷺ foretelling of the killing of ʿAlī ibn Abī Ṭālib—and it came to pass exactly as he foretold

Imām Aḥmad related²—ʿAlī ibn Baḥr told us; ʿĪsā ibn Yūnus told us; Muḥammad ibn Isḥāq told us; he said: Yazīd ibn Muḥammad ibn Khuthaym al-Muḥāribī narrated to me, from Muḥammad ibn Kaʿb [al-Quraẓī; from Muḥammad ibn Khuthaym], from ʿAmmār ibn Yāsir, who said:
“The Messenger of Allah ﷺ said to ʿAlī—when he left him in charge during the expedition of al-ʿUshayrah—‘O Abū Turāb!’ (for he noticed dust upon him). ‘Shall I not inform you of the two most wretched of men?’ We said, ‘Indeed, O Messenger of Allah!’ He said, ‘The little red-haired man of Thamūd who hamstrung the she-camel, and the one who will strike you, O ʿAlī, on this’—pointing to the top of his head—‘until this’—pointing to his beard—‘is drenched.’”

Al-Bayhaqī³ likewise narrated—through al-Ḥākim, al-Aṣamm, al-Ḥasan ibn Makram, Abū al-Naḍr, Muḥammad ibn Rāshid, and ʿAbd Allāh ibn Muḥammad ibn ʿAqīl—from Faḍālah ibn Abī Faḍālah al-Anṣārī (whose father fought at Badr):
“I went out with my father to visit ʿAlī ibn Abī Ṭālib when an illness had left him severely weakened. My father said to him, ‘What keeps you in this dwelling of yours? If death should overtake you here, only some Bedouins of Juhaynah would be with you! They would have to carry you to Madinah, and if you were to die there, your Companions would tend to you and pray over you.’ ʿAlī replied, ‘The Messenger of Allah ﷺ covenanted with me that I would not die until this’—and he touched his beard—‘is stained…’