Al- Allaamah Rabee Bin Haadi Al-Madkhali (may Allaah preserve him) stated:

And that one who does not know the books of refutations, even if he has memorized of knowledge that which is to be memorized, then indeed – may Allaah bless you – he is (still) on an unstable position. We have seen many who know, but then they fell into misguidance…. Listen to full audio here: