The following is a thought-provoking sermon, attributed to Caliph `Ali (may Allah be well pleased with him).
Among the people most detested before Allah are two: One whom Allah has [forsaken and] entrusted to his own self, and so he has transgressed from the sound path and is enamored with speech of [reprehensible] innovation and invitation towards error. He is therefore a tribulation for those who are afflicted with him, astray from the guidance of those preceding him, misleading those who follow him in his life or after his death, carrying [part of the burden of] sins of others, and mortgaged for his own misdeeds.
[The second is] a man who has amassed ignorance. He moves among the ignorant of the ummah [to deceive them] and hastens to the darknesses of tribulation, while being blind to the advantages of tranquil satisfaction. Pseudo-men have named him a scholar but he is not so. He goes out in the early morning, and amasses an abundance of things which are better to be lacking in than to have in plenty, until, when he has quenched his thirst from polluted, brackish water and gathered purposeless things, he sits as a judge amongst people, taking upon himself to clarify what has been perplexing to others. If an enigmatic matter comes before him, he prepares for it some crumbling stuffing and passes it off as a certainty.
Thus is he entangled in the confusion of doubts, as in a spider’s web. He does not know whether he was right or wrong; if he is right he fears he may have erred, while if he is wrong he hopes he is right. He is ignorant, wandering astray in the darknesses of ignorance, weak-sighted and riding aimlessly. He has not obtained a firm grasp on knowledge. He wrecks the [Scriptural] Narrations, just as the wind scatters and breaks up dry leaves. By Allah, he is not competent to issue verdicts about the matters that come to him, nor is he fit for the position assigned to him. He does not consider knowledge to be contained in anything which he does not recognize, nor does he consider there could be any other way/viewpoint (literally: madhhab) beyond what he has reached. If anything is unclear to him he keeps quiet about it, because of what he knows of his own ignorance. Shed blood cries out against the injustice of his verdicts, and estates [of the deceased] screech against him.
I complain to Allah about persons who live ignorant and die misguided. There is nothing more unprofitable for them than the Book [of Allah] when it is recited as it should be recited, nor anything more lucrative or valuable [in their eyes] than the Book when its words are distorted from their contexts. There is nothing more unrecognisable to them than good, nor anything more familiar to them than wrong.
[Source: Nahj al-Balaghah, Sermon 17]”