And the one who gives fatawa without knowledge is more astray than the ignorant one. Because the ignorant one says: “I do not know.” And he knows his capability as well as being truthful. As for the one who compares himself with the most knowledgeable of scholars, rather he may even favor himself over them, and in so doing he will misguide himself as well as the people, and he will make mistakes in issues that even the smallest of the students of knowledge know.
So the evil of this person is tremendous and his danger is great.
Kitaabul ‘Ilm. P: 164