(He said) Korah said: (I have been given it) this wealth (only on account of knowledge I possess) because Allah knows that I deserve it; it is also said that this means: he made gold from his knowledge of alchemy. (Knew he not) i.e. Korah (that Allah had destroyed already of the generations before him men who were mightier than Him in strength) who were physically stronger than him (and greater about following) and greater in respect to the wealth and men they had? (The guilty are not questioned of their sins) the idolaters will not be asked on the Day of Judgement about their sins because they will be known through distinct marks.
