He said: “Because he was the first to gather us for the Friday prayer at the hollow of al-Nabīt, in the lava field of the Banū Bayāḍah, at a watering place called Nuqayʿ al-Khaḍimāt.” I said: “How many were you that day?” He said: “Forty.”

(1) Its chain is sound. Muḥammad ibn Isḥāq explicitly stated that he transmitted it orally, as recorded by Ibn Ḥibbān and others, so any suspicion of tadlīs is removed.
It was also recorded by Ibn Mājah (1082) via ʿAbd al-Aʿlā ibn ʿAbd al-Aʿlā, from Muḥammad ibn Isḥāq, with this chain.
It appears in Ṣaḥīḥ Ibn Ḥibbān (7013).
His saying “hazm”: Ibn al-Athīr said it is a place in Medina.
“Al-Nabīt”: Yāqūt said in Muʿjam al-Buldān, under the entry (hazm): a sub-tribe of the Anṣār, namely ʿAmr ibn Mālik ibn al-Aws. “Bayāḍah” is also a sub-tribe of the Anṣār, namely Bayāḍah ibn ʿĀmir ibn Zuraq ibn ʿAbd Ḥārithah ibn Mālik ibn Ghaḍb ibn Jusham ibn al-Khazraj.
“Nuqayʿ al-Khaḍimāt”: a place in the vicinity of Medina, as Ibn al-Athīr said. As for “al-Khaḍimāt,” it is said in Sharḥ al-Qāmūs: with fatḥ on the letters, as al-Jalāl vocalized it, or like “Farḥāt” as al-Sayyid al-Samhūdī vocalized it, or with kasrah as the author vocalized it in his Tārīkh al-Madīnah.
Al-Khaṭṭābī said: In this ḥadīth there is jurisprudential evidence that the Friday prayer is permissible in villages just as it is permissible in cities and towns, for the lava field of the Banū Bayāḍah is said to be a village about a mile from Medina. Al-Shāfiʿī used it as evidence that the Friday prayer is not valid with fewer than forty free, settled men, because this Friday prayer was the first of the Friday prayers to be instituted, so all its characteristics were considered binding in it, since it was an explanation of an obligatory general command, and the explanation of an obligatory general command is obligatory.
It has been related that ʿUmar ibn ʿAbd al-ʿAzīz required forty for the Friday prayer, and Aḥmad ibn Ḥanbal and Isḥāq adopted this view, except that ʿUmar added to the number of forty the condition that a governor be among them. He said: The governor is not a condition according to al-Shāfiʿī. Mālik said: If there is a group in a village whose houses are contiguous, and it has a market and a mosque in which the Friday prayer is held, then the Friday prayer is obligatory upon them, and he did not mention a fixed number. His view regarding the governor is like al-Shāfiʿī’s view.
The proponents of raʾy said: There is no Friday prayer except in a congregational city, and it is valid in their view with four.
Al-Awzāʿī said: If there are three, they may pray the Friday prayer if a governor is among them. Abū Thawr said: It is like the rest of the prayers regarding the number.