Al-Kattani records in ar-Risāla al-Mustatirafa (p. 47) that “it appears in a thin volume; there is another about three times its size, containing many mawqūf and maqṭūʿ reports.” Neither Brockelmann nor Szekkin mention it, and I have not encountered it. Al-Hāfiẓ Ibn Ḥajar states in the Introduction to al-Maṭālib al-ʿĀliyyah (vol. 1, p. 4) that he examined it in full and appended its additional hadiths to the Six Canonical Books in the work cited. Al-Bukhārī (may Allah have mercy on him) transmits in his Ṣaḥīḥ via its isnād several ḥadīths on the divine Attributes; see, for example, Ṣaḥīḥ al-Bukhārī, vol. 8, p. 174, Kitāb al-Tawḥīd – chapter “When You created by My Hand.” See also: Tabaqāt al-Ḥanābila (Ibn Abī Ya‘là) 1:341–345; Tadhkirat al-Ḥuffāẓ (al-Dhahabī) 2:421, 423; Tahdhīb al-Tahdhīb (Ibn Ḥajar) 1:107–109; Kashf al-Ẓunūn (Ḥājjī Khalīfa) 2:1684; al-A‘lām (al-Zarkalī) 8:108; Ma‘jam al-Muʾallifīn (Kahḥāla) 12:224. (1) He is Abū Ya‘qūb Isḥāq ibn Ibrāhīm ibn Mukhlad al-Ḥanzalī al-Marwazī, known as Ibn Rahwayah, one of the imams of Islam and a distinguished scholar. Born in 161 AH (d. 238 AH), he left a Musnad in manuscript. Ibn Ḥajar notes in the Introduction to al-Maṭālib al-ʿĀliyyah (1:4): “I encountered several incomplete musnads, such as the Musnad of Isḥāq ibn Rahwayah; I examined roughly half of it and traced its contents.” Among the reports he cites from this portion in al-Maṭālib under the chapter on the Attributes are ḥadīths 2990 and 2991 (3:99). Brockelmann writes in Geschichte der arabischen Litteratur (3:157): “The fourth part of his Musnad is in Cairo and is slated for publication in Hyderabad.” Al-Kattani adds in ar-Risāla al-Mustatirafa (p. 49) that “he dictated the Musnad and the Tafsīr entirely from memory—he related nothing except what he had memorized, having committed seventy thousand ḥadīths to heart, and his Musnad comprises six volumes.” See also: al-Jarḥ wa’l-Ta‘dīl (Ibn Abī Ḥātim) 2:209; Ḥilyat al-Awliyāʾ (Abū Nu‘aym) 9:234–238; Tārīkh Baghdad (al-Baghdādī) 6:345–355; Tabaqāt al-Ḥanābila (Ibn Abī Ya‘là) 1:109; Wafayāt al-A‘yān (Ibn Khalkān) 1:199; Kashf al-Ẓunūn (Ḥājjī Khalīfa) 2:1678.