Abu az-Zinad Abdullah ibn Dhakwan: I have not seen anyone more knowledgeable of the Sunnah than him, and once: I have not seen anyone more intelligent than him
Abu Hatim ibn Habban al-Busti: He was one of the leaders of the Tabi'in, one of the best of his time in knowledge, literature, and fiqh, and he was silent
Ahmad ibn Salih al-Jili: He was one of the best of the Tabi'in and their jurists, and once: Trustworthy, pure, a righteous man
Ayyub ibn Abi Tamimah as-Sakhtiyani: I have not seen a better man than him
Ibn Hajar al-Asqalani: Trustworthy
Adh-Dhahabi: One of the leading Imams
Sufyan ibn Uyainah: He was the best of his time, and he once said: The most knowledgeable of the people about the hadith of Aisha
Malik ibn Anas: He was one of the jurists of this Ummah
Muhammad ibn Sa'd al-Waqidi: Trustworthy
Muhammad ibn Umar al-Waqidi: Trustworthy and he was a high-ranking scholar, jurist, imam, pious, and narrated many hadiths
Mus'ab ibn Abdullah az-Zubayri: From the best of the Tabi'in
Yahya ibn Sa'id al-Ansari: We did not find anyone in Medina superior to al-Qasim
Yahya ibn Ma'in: Al-Qasim and Salim, their hadith is close to being equal