He transmitted ḥadīth from Thawr ibn Yazīd, Ḥarīz ibn ʿUthmān, Aflah ibn Ḥumayd, Shibl ibn ʿAbbād, Ibrāhīm ibn Nāfiʿ, Sufyān al-Thawrī, and a number of others.

Those who in turn narrated from him include Muḥammad ibn ʿAbd Allāh ibn ʿAmmār; Ṣāliḥ and ʿAbd Allāh, the two sons of ʿAbd al-Ṣamad ibn Abī Khidāsh; as well as ʿAlī ibn Ḥarb and his brother Aḥmad ibn Ḥarb—the two Mosulis.

Abū Ḥātim declared him reliable.

Yazīd ibn Muḥammad al-Azdī states in his History of Mosul: “He was an ascetic, God-fearing man, one of Sufyān’s disciples. He travelled widely and wrote down what he heard from the scholars he met in the Ḥijāz, Kūfa, Baṣra, Syria, and Mosul. He memorised ḥadīth and was versed in jurisprudence.”

Bishr ibn al-Ḥārith said, “People used to say that Qāsim al-Jarmī was one of the abdāl. He did not resemble his companions in dress; his clothing was even humbler than that of al-Muʿāfā and Zayd ibn Abī al-Zarqāʾ.”

ʿAlī ibn Ḥarb related: “I entered the house of Qāsim ibn Yazīd and saw some carob lying in a corner, from which he sustained himself, together with a sword and a muṣḥaf (copy of the Qurʾān).”

Someone once saw Qāsim in a dream carrying the city of Mosul on his shoulder, having taken it from the shoulder of Fath al-Mawṣilī. Qāsim interpreted the dream for the onlooker, saying, “Mosul will be ruled by Fath; he will die, and then it will come under your charge.”

Bishr al-Ḥāfī also said, “Qāsim had memorised the legal questions and the ḥadīths. Al-Muʿāfā told us, ‘Listen to him, for he is trustworthy and reliable.’”

Yazīd ibn Muḥammad further records in his History: ʿAbd Allāh ibn al-Mughīra, the client of Banū Hāshim, narrated to us from Bishr al-Ḥāfī that when the companions of Sufyān were discussed they unanimously gave precedence to al-Muʿāfā ibn ʿImrān. Bishr remarked, “Al-Muʿāfā has been granted fame, but my eyes have never seen the like of Qāsim al-Jarmī—may Allah have mercy on him.”