Aḥmad ibn Kāmil the judge said, “Abū ʿUbayd was outstanding in both his piety and his learning—devout, and masterful in the various branches of the Islamic sciences: Qur’an, jurisprudence, Arabic, and historical reports. His narrations were sound, his transmissions reliable. I know of no one who ever impugned him in anything to do with his conduct or his religion.” (1)

We have been informed that ʿAbd Allāh ibn Ṭāhir, the governor of Khurāsān, said, “People are four: Ibn ʿAbbās in his time, al-Shaʿbī in his time, al-Qāsim ibn Maʿn in his time, and Abū ʿUbayd in his time.” (2)

Ibrāhīm ibn Muḥammad al-Nassāj related: I heard Ibrāhīm al-Ḥarbī say, “I met three men the like of whom women will never again bear. I saw Abū ʿUbayd, and could liken him only to a mountain into which a soul had been breathed. I saw Bishr ibn al-Ḥārith, and could picture him only as a man kneaded from head to toe out of pure intellect. And I saw Aḥmad ibn Ḥanbal, and it was as though Allah had gathered for him the knowledge of the early generations: from every discipline he could say what he wished and withhold what he wished.” (3)

Mukram ibn Aḥmad reported that Ibrāhīm al-Ḥarbī said, “Abū ʿUbayd was like a mountain into which life had been breathed; he excelled at everything except hadith with the craftsmanship of Aḥmad and Yaḥyā.” (4)

Abū ʿUbayd first tutored a young boy in the quarter of Bishr, then joined Thābit ibn Naṣr al-Khuzaʿī as tutor to his son. When Thābit governed Ṭarsūs for eighteen years, he appointed Abū ʿUbayd as its judge for the same span, and during that time Abū ʿUbayd was too occupied to continue writing down hadith. (5)