Imam Ibn ul Qayyim, may Allah be pleased with him, said:
“The Mufti or the ruler, will not be able to give a correct judgement unless he has two types of knowledge.
The first type of knowledge is, correctly comprehending the reality [of the matter], and being able to derive the facts from it’s “qaraa’in” [outward indicating factors] and it’s signs and symbols, up until he has comprehensive knowledge of the matter.
The second type of knowledge, is the obligation of comprehending the reality of it’s ruling found in the Book of Allah, or upon the tongue of His Messenger, sallallahu alayhi was salama, based upon it’s reality, and then correctly applying the first type of knowledge, with the second type.”
[“I’laam al muwaqqi’een Volume: 1 Page: 87”]