The example that best represents Imam Abu Hanifa’s restraint is when a layman came to Abu Hanifa and asked him a question regarding a fatwa of Hasan al-Basri. Abu Hanifa stated, Hasan erred. So the man said to Abu Hanifa, You say that Hasan erred, son of a *****. Abu Hanifa did not redden or get upset. He said,By Allah, Hasan erred and Abullah ibn Masud was correct.
[source: The Four Imams: Their Lives, Works, and their Schools of Thought, Muhammad Abu Zahras book.]