Al-Bayhaqī transmitted this very wording from al-Ḥākim Muḥammad ibn Nuʿaym al-Ḍabbī.
Al-Ḥākim said: He is Isḥāq ibn Mūsā ibn ʿImrān, one of the foremost Shāfiʿī authorities and a wide-travelled seeker of ḥadith. He came from the rural district of Iṣfarāʾīn; he studied law under Abū Ibrāhīm al-Muzanī, heard the Mabsūṭ from al-Rabīʿ, and committed ḥadith to writing in Khurasān, the two Iraqs, the Ḥijāz, Egypt, and Syria.
He added: He composed many works.
In Khurasān he studied under Qutaybah ibn Saʿīd, Ibrāhīm ibn Yūsuf, Isḥāq ibn Rāhwayh, ʿAlī ibn Ḥujr, and their contemporaries;
in al-Jibāl under Muḥammad ibn Muqātil, Ibn Aḥmad, and a number of others;
in Baghdad under Manṣūr ibn Abī Muzāḥim, Muḥammad ibn Bakkār, ʿUbayd Allah al-Qawārīrī, Aḥmad ibn ʿImrān al-Akhnasī, and Abū Muslim al-Wāqidī;
in Basra under ʿAbd al-Aʿlā ibn Ḥammād al-Narsī, ʿAbd Allah ibn Muʿāwiyah, Bundār, and Abū Mūsā;
in Kufa under ʿUthmān ibn Abī Shaybah, his brother al-Qāsim, Jubārah ibn al-Mughallis, Abū Kurayb, and ʿAbd Allah ibn ʿUmar ibn Abān;
in the Ḥijāz under Ibrāhīm ibn Muḥammad al-Shāfiʿī, Ibrāhīm ibn al-Munḏir, Abū Muṣʿab, Yaʿqūb ibn Ḥumayd, and several others;
in Syria under Hishām ibn ʿAmmār, Duḥaym, Aḥmad ibn Abī al-Ḥawārī, and scholars of their standing;
and in Egypt under Muḥammad ibn Rumḥ, ʿĪsā ibn Ḥammād, Harmalah, Abū al-Ṭāhir ibn al-Sarraḥ, and their peers.
Those who narrated from him include: Abū ʿAmr al-Ḥīrī, Abū ʿAwānah al-Iṣfarāʾīnī, Muʾammal ibn al-Ḥasan, Muḥammad ibn ʿAbdak and others, as well as Abū ʿAbd Allah Muḥammad ibn Yaʿqūb al-Shaybānī.
Muḥammad ibn ʿAbdak al-Iṣfarāʾīnī said: Abū Yaʿqūb al-Iṣfarāʾīnī passed away there in the month of Ramaḍān, in the year 284 AH.
Al-Ḥākim then said: Abū ʿAbd Allah Muḥammad ibn Yaʿqūb the ḥāfiẓ informed us; he related