If the affair of a person is hidden from you–the one whose books and cassettes are famous and his fame is widespread–then ask those who are well acquainted with him and those who know about his state of affairs. That is because neither is the Sunnah hidden nor are its people. A man’s Tazkiyah (i.e. the clear witness that he is upright upon the Sunnah) are his own actions. His Tazkiyah are his own actions that he is upon the Sunnah. It is the witness and the people mention him with it during his life and after his death.
There is none who hides behind the Sunnah– the people beguiled by him, gathered around him to learn, adhered to him, became dependent on him and accepted everything he said–except that Allaah will reveal his affair, uncover and expose his concealed state of affairs to specific individuals and to the general public, regarding what was hidden and apparent of his deception, his mixing truth with falsehood, his plots and deceitful practices. Allaah facilitates men of virtue, intelligence, wisdom, strength and exceptional natural ability–possessors of knowledge, skill and sound understanding of the religion–through whom He (Allaah) unveils the affair of that trickster, dubious and deceitful person.
Therefore, it is incumbent upon you that when the state of that person is made clear–the one whose fame is widespread etc.–then you should be cautious of him as long as he was warned against by those people of knowledge and Imaan who are upon the Sunnah; for indeed they will unveil his affair with evidences. And there is no hindrance in unveiling the state of that person who has been warned against by a scholar or scholars with the appropriate etiquettes and in a good manner because that scholar will say to you: “I saw this and that in him, and I saw this and that in the book of such and such, or I heard this or that in the cassette of such and such.” Therefore, you have clear evidence that will unveil what was hidden from you, and that the one whose fame is widespread and his speech is pleasant is one who hides something of innovation and plotting, which cannot be compared to what he manifests from the Sunnah.
Secondly: The one who knows of a mistake and it is clear to him, then it is not permissible for him to blindly follow a scholar to whom an affair is hidden. And indeed you already heard yesterday that the scholars are not infallible in their Ijtihaadaat. Therefore, it is not permissible to adopt them (i.e. the mistakes of the scholars) as a methodology (to follow).