Our Deen, Islam, consists of many a’amaal (actions). For a’amaal to come alive in our lives, the requirement is knowledge. Thus if our knowledge is correct, our actions will be correct and ultimately our Islam will be correct. Therefore in essence the knowledge we possess is our Deen. We need to be very cautious about whom and where we acquire our knowledge from. The source must be authentic and the person must be reliable. The Great Tabi’ee Muhammad ibnu Sireen (rahimahullah) said: "This knowledge is your Deen, so be extremely cautious regarding its source, (Saheeh Muslim)."
When we buy a car we do not buy it based on the sound of its hooter - that if the hooter sounds good the car must be good. Rather we check its engine and whether it has quality parts that are well assembled and serviced. In the same way when it comes to our Deen, we need to check if the speaker is a qualified ‘Aalim who studied under the guidance of ‘Ulama. He should not be some self-taught internet/google “scholar” who merely sounds good, so we assume he must be good. One of the greatest fears Rasulullah (sallallahu alaihi wasallam) had for his Ummah was the danger of hypocrites who have great command over the language (ie. They have the gift of the gab), (Majma’uz Zawaaid, vol. 1, pg. 445).
Let us not be fooled merely by a person’s oratory skills and his ability to quote Arabic phrases. Of absolute importance is his “engine” (his heart), his motivation, his intention, his link with his teachers and above all, his commitment to Deen and the Sunnah of Rasulullah (sallallahu alaihi wasallam). Imaam Maalik (rahimahullah) said: "Knowledge should only be acquired from the one who has studied it and acquired it in the company of the “Men of knowledge”, he has understood it, he practices on it and he has piety and the fear of Allah Ta’ala coupled with it." (Adabul Ikhtilaaf, pg. 165).
Taken from Al-Haadi