Abul Hasan ‘Ali ibn Khalid reported to me from Zaid ibn al-Husayn al-Kufi, who reported from Ja'far ibn Nujayh, who reported from Jandal ibn Waliq al-Taghlabi, who reported from Muhammad ibn Umar al-Mazini, from Abu Zaid al-Ansari, from Saeed ibn Bashir, from Qutadah, from Saeed ibn al-Musayyib, who said:
I heard a man ask Ibn Abbas about ‘Ali ibn Abi Talib, peace be upon him. Ibn Abbas told him: "Surely, ‘Ali is the one who prayed towards both the Qiblas and swore allegiance to the Prophet on both occassions. He never worshipped an idol nor did he divine by the arrows. He was born a Muslim and did not associate any partner to Him, even for a wink."
The man said: "I did not ask you that! I want to know from you about the sword which he proudly carried over his shoulder, came to Basrah and killed forty thousand. Then he went to Syria, confronted the Arab leaders, pitting one against the other and then killed them. Then he came to Nahrawan and killed the Muslims upto the last one."
Ibn Abbas told him: "Who do you think is more knowledgeable, ‘Ali or myself?" He said: "If I had thought ‘Ali to be more knowledgeable, I would not have come to you!"
Upon hearing this, Ibn Abbas was enraged and he said: "May your mother mourn you! ‘Ali is the one who taught me. And his knowledge is from the Prophet, peace be upon him and his progeny, and the Prophet received knowledge from Allah, Most High. So, the knowledge of the Prophet is from Allah, and ‘Ali's knowledge is from the Prophet and my knowledge is from ‘Ali. And the knowledge of all the companions of Muhammad, peace be upon him and his progeny, when compared to ‘Ali's knowledge is just like a drop in the seven oceans."