Abu Hatim Al-Razi: If Ath-Thawri disagreed with Ma'sar, the ruling is with Ma'sar, for he is the Mushaf (Quran). And once he said: Ma'sar is more pious, more knowledgeable in Hadith, and higher in Isnad than Ath-Thawri, and he is more pious than Hammad bin Zaid.
Abu Hatim bin Hibban Al-Busti: He mentioned him among the trustworthy and said: He was a reliable authority, sound in Hadith. And once, among the famous scholars of the cities: He was pious.
Abu Dawud Al-Sijistani: Ma'sar is a companion of Sheikhs, he narrated from a hundred from whom Ath-Thawri did not narrate.
Abu Zar'ah Al-Razi: Trustworthy
Abu Abdillah Al-Hakim Al-Naysaburi: One of the Imams of the Muslims and their trustworthy ones.
Abu Nuaym Al-Asbahani: Trustworthy, excellent
Abu Nuaym Al-Fadl bin Dukin: Ma'sar is more sound, then Sufyan, then Shu'ba. And once: Ma'sar was doubtful in his Hadith, but he would not err in anything of his Hadith except in one Hadith.
Ahmad bin Hanbal: Trustworthy. And once: He was trustworthy, excellent, his Hadith is the Hadith of the people of truth. And once: The trustworthy ones are like Shu'ba and Ma'sar.
Ahmad bin Salih Al-Jilli: Trustworthy, sound in Hadith.
Ibn Hajar Al-Asqalani: Trustworthy, sound, excellent
Al-Dhahabi: One of the flagships. And once: An Imam, sound, Sheikh of Iraq, Hafiz, from the generation of Shu'ba. And once: Most of his Hadith is from the people of his city, except Qatadah, as if he traveled to him.
Khalid bin Dinar Al-Basri: Trustworthy
Sufyan Ath-Thawri: When we disagreed about something, we would ask Ma'sar about it. And once: There was no one like him in his time.
Sufyan bin Uyainah: He was considered among us from the sources of truth. And once: I did not find anyone better than Ma'sar.
Sulaiman bin Mihran Al-A'mash: His doubt is like the certainty of others.
Shu'ba bin Al-Hajjaj: We used to call him the Mushaf (Quran). And once: Ma'sar in Kufa is like Ibn 'Aun in Basra. And once: The devil of Ma'sar weakens him, making him doubt the Hadith.
Abdullah bin Dawud Al-Khuraibi: He was called the Mushaf (Quran) because of his few mistakes and his memorization. And once: There is no one who has not been criticized except Ma'sar.
Ali bin Al-Madini: Trustworthy, sound Hadith, firm
Muhammad bin Bishr Al-'Abdi: Ma'sar had a thousand Hadiths, and I wrote them except for ten.
Muhammad bin 'Ammar Al-Mawsili: An authority, and who in Kufa is like him?
Hisham bin Urwah Al-Qurashi: No one better than Ayyub and Ma'sar came to us from Iraq. And once: I did not see anyone in Kufa like Al-Ru'as.
Wakee' bin Al-Jarrah: The doubt of Ma'sar is like the certainty of a man.
Yahya bin Sa'id Al-Qattan: I have not seen anyone like him, he was one of the most sound people.
Yahya bin Ma'in: Trustworthy, Ma'sar did not travel for a single Hadith. And in the narration of Ibn Mahriz: He did not hear anything definitive except in Kufa, his hearing was only from those who came to Kufa.
Ya'la bin 'Ubaid At-Tanafi: Ma'sar had combined knowledge and piety.