- ʿUmar ibn al-Khaṭṭāb: in al-Mustadrak (4/449); al-Ḥākim declared it authentic, and al-Dhahabī concurred.
Thus, the hadith is unquestionably authentic. I have cited it only because of this addition, and you have learned that its chain of transmission to Yazīd ibn Hārūn is weak. Abū Bakr al-Khaṭīb likewise narrated it through this chain in his book Sharaf Aṣḥāb al-Ḥadīth (folio 34/1). In al-Fatḥ (13/249, Būlāq edition), al-Ḥāfiẓ attributed it to al-Ḥākim’s ʿUlūm al-Ḥadīth, but I believe this to be an error, for I searched for it there and did not find it. Rather, I found there what follows from Imām Aḥmad.
Yet this addition is well known and established from a group of hadith scholars belonging to the generation of Yazīd ibn Hārūn and others. They are:
- ʿAbd Allāh ibn al-Mubārak (118–181 AH). Al-Khaṭīb narrated through his chain from Saʿīd ibn Yaʿqūb al-Ṭālaqānī, or someone else, who said:
“Ibn al-Mubārak mentioned the hadith of the Prophet (may Allah bless him and grant him peace): ‘A group shall continue …’ Ibn al-Mubārak said: ‘In my view, they are the scholars of hadith.’”
- ʿAlī ibn al-Madīnī (161–234 AH). Al-Khaṭīb also narrated, by way of al-Tirmidhī—and this is in his Sunan (2/30)—after citing the hadith through the previously mentioned narration of al-Muzanī (no. 5), then said: