From – Shaykh Muhammad al-Yaqoubi’s “al-Fatwa wa al-Qada fi al-Islam”, 1433 AH:

The Messenger of Allah (salla Llahu ‘alayhi wa sallam), warned against hastening to give a fatwa or rushing to give an answer:

The quickest of you in giving fatwa is the quickest one to enter the Fire,

A famous hadith related by Al-Darimi.

The Gnostic Ibn `Ata’illah as-Sikandari (rahimahu Llah) says in his Aphorisms:

When I see a person answering every question presented to him, speaking about all that he has witnessed and declaring all that he knows, I take these as proofs of his ignorance.