Abu Hatim al-Razi: He was a righteous man, but he was somewhat forgetful. I heard a fabricated hadith from him, which he narrated on the authority of Ibn Uyainah. However, he was truthful.
Abu Hatim ibn Hibban al-Busti: He mentioned him among the trustworthy narrators.
Ahmad ibn Hanbal: He was asked, "From whom should we write [hadiths]?" He replied, "As for Makkah, [write from] Ibn Abi Umar."
Ibn Hajar al-Asqalani: Trustworthy
Al-Dhahabi: The Hadith Memorizer
Muslim ibn al-Qasim al-Andalusi: He is alright.