Al-Ḥāfidh al-Dhahabī said:

He was an āyah (sign) in intelligence and in rapid comprehension, a leader in knowledge of the Book, the Sunnah and differences (of opinion) ... if tafsīr was mentioned, he was the carrier of its flag, and if the jurists were mentioned, he was their mujtahid muṭlaq, and if the Ḥuffādh gathered and he spoke, they became mute, and he enumerated (cited from memory), and they were silent, and he was rich, and they were bankrupt. And if the theologians were named, he would be the unique of them and he would be their source, and if Ibn Sīnā emerged in the absence of the Philosophers, he would subdue them, diminish them, uncover their veils and reveal their flaws...

As quoted from al-Dhahabī by Ibn Shākir in Fuwāt al-Wafiyāt, through Muḥammad al-Shaybānī in al-Tawḍīḥ al-Jaliyy (p. 59).

From the forthcoming publication, "The Creed of the Early Kullabi Ash'aris."