Surah 3. Aal-Imran, Ayah 71

There are many ways of preventing the access of people to the truth. One is to tamper with it, or trick it out in colours of falsehood: haf-truths are often more dangerous than obvious falsehoods. Another is to conceal it altogether. Those who are jealous of a prophet of Allah, whom they actually see before them, do not allow his credentials or virtues to be known, or vilify him, or conceal facts which would attract people to him. When people do this of set purpose, against their own light ("of which ye are yourselves witnesses"), they are descending to the lowest depths of degradation, and they are doing more harm to themselves than to anyone else.