إن منكم من يقاتل على تأويل هذا القرآن كما قاتلتُ على تنزيله فاستشرفنا وفينا أبو بكر وعمر. فقال لا ولكنه خاصف النعل فجئنا نبشره قال وكأنه قد سمعه.
The Prophet salla Llahu ‘alayhi wa sallam said, “There is someone from among you who will fight for the (correct) interpretation of this Qur’an, just as I fought for its revelation.” We stretched ourselves up (hoping to be the person the Prophet salla Llahu ‘alayhi wa sallam was referring to), and Abu Bakr and ‘Umar were (also) amongst us. The Prophet salla Llahu ‘alayhi wa sallam said, “No. Rather, it is khasif al n’al (the repairer of the sandals) (referring to ‘Ali).” We came to give him (i.e. ‘Ali) the glad tidings (of what the Prophet salla Llahu ‘alayhi wa sallam said). He (the narrator) said, “It was as if ‘Ali heard it (himself).”
Abu Sa’id al Khudri’s radiya Llahu ‘anhu version of this hadith is authentic. It has also appears with weak chains of transmission from ‘Ali, ‘Abdul Rahman ibn Bashir, Abu Dharr, and al Akhdar ibn Abi al Akhdar radiya Llahu ‘anhum.
Imam Ahmed—and others—narrates the hadith of Abu Sa’id al Khudri with a jayyid (good) chain of transmission as follows:
عن أبي سعيد الخدري قال كنا جلوسا ننتظر رسول الله صلى الله عليه وسلم، فخرج علينا من بعض بيوت نسائه قال فقمنا معه فانقطعت نعله فتخلف عليها علي يخصفها فمضى رسول الله صلى الله عليه وسلم ومضينا معه ثم قام ينتظره وقمنا معه فقال…
We were seated in anticipation of the Messenger of Allah salla Llahu ‘alayhi wa sallam. He came out to us from (one of) the houses of his wives. He (Abu Sa’id) said, “We stood up with him when his sandal (strap) severed. ‘Ali remained behind repairing it. The Prophet salla Llahu ‘alayhi wa sallam carried on walking and we walked with him. Then he salla Llahu ‘alayhi wa sallam stood waiting for ‘Ali and we stood (waiting) with him. He said… (the rest of the hadith).
Al Hakim authenticated this hadith. Ibn al Jawzi discovered an ‘illah (hidden flaw) in this hadith. I have explained how he erred in the original work. Al Albani (also) authenticated this hadith.
The remaining chains of transmission are mentioned in the original work, none of which are authentic.
In this hadith, Nabi salla Llahu ‘alayhi wa sallam was referring to ‘Ali’s fighting the Khawarij; when they interpreted the Qur’an the wrong way. And so ‘Ali sent Ibn ‘Abbas radiya Llahu ‘anhuma to them. Ibn ‘Abbas radiya Llahu ‘anhuma disputed with them, on account of which two thousand returned. The others were all killed in their misguidance.
Imam al Nasa’i, al Hakim, and others narrate the incident of Ibn ‘Abbas’s dispute with them.
 Ibn al Jawzi: al ‘Ilal al Mutanahiyah.
 Al Albani: Silsilat al Ahadith al Sahihah, hadith no. 2487.
 Imam al Nasaʾi: al Sunan al Kubra, hadith no. 8522; al Hakim: Mustadrak al Hakim, hadith no. 2656.