Abū Ḥātim al-Rāzī said, “He is more exact than al-Aʿmash; he neither mixes narrations nor practices tadlīs (concealing one’s source), unlike al-Aʿmash.”

Sufyān ibn ʿUyaynah remarked, “Manṣūr was enrolled in the diwān (military register). Whenever his turn came, he would dress, go out, and stand guard—that is, at the ribāṭ (frontier garrison).”

Abū Nuʿaym al-Mullāʾī relates: “I heard Ḥammād ibn Zayd say, ‘I saw your companion Manṣūr ibn al-Muʿtamir; he belonged to this khashabiyyah (a Shiʿi faction), and I do not think he ever lied.’”
I say: the khashabiyyah are the Shīʿah.

Yaḥyā ibn Saʿīd al-Qaṭṭān declared, “Manṣūr was among the most reliable of people.”

The well-known story of the ḥāfiẓ Abū Bakr al-Bāghandī—recorded in al-Muʿjam al-Ghassānī—relates that he was reading selected reports to a shaykh who kept saying, “How you weary me! You have more ḥadīth than I do and remember them better.” Abū Bakr replied, “I have come to this discipline because I once saw the Prophet ﷺ in a dream. I did not ask him for supplication; instead I said, ‘Messenger of Allah, who is sounder in ḥadīth, Manṣūr or al-Aʿmash?’ He answered, ‘Manṣūr, Manṣūr.’”

Isḥāq ibn Ṭāriq informed us; Ibn Khalīl informed us; Abū al-Makārim al-Labbān informed us; Abū ʿAlī al-Ḥaddād informed us; Abū Nuʿaym informed us; Abū Muḥammad ibn Ḥayyān narrated to us; Muḥammad ibn Yaḥyā narrated to us; Azhar ibn Jamīl narrated to us; Sufyān ibn ʿUyaynah said: “I saw Manṣūr ibn al-Muʿtamir and asked, ‘What has Allah done with you?’ He replied, ‘I almost met Allah—Exalted is He—with the deeds of a prophet.’ Sufyān added, ‘Manṣūr fasted for sixty years, spending every night in prayer and every day in fasting.’”

Abū Nuʿaym al-Mullāʾī said, “Manṣūr died after the arrival of the Sudān—that is, the Musawwada, meaning the ʿAbbāsid family.”

Aḥmad ibn Zuhayr reported: “I heard Ibn Maʿīn say: ‘Manṣūr died in the year 133 AH.’”
Muḥammad ibn ʿAbd Allāh ibn Numayr and Shabāb al-ʿUṣfurī also dated his death to that same year.