Adam Clarke on Matthew 15:19

Out of the heart - In the heart of an unregenerate man, the principles and seeds of all sin are found. And iniquity is always conceived in the heart before it be spoken or acted. Is there any hope that a man can abstain from outward sin till his heart, that abominable fountain of corruption, be thoroughly cleansed? I trow not.

Evil thoughts - Διαλογισμοι πονηροι, wicked dialogues - for in all evil surmisings the heart holds a conversation, or dialogue, with itself. For φονοι, murders, two MSS. have φθονοι, envyings, and three others have both. Envy and murder are nearly allied: the former has often led to the latter.

Blasphemies - I have already observed, Mat 9:3, that the verb βλασφημεω, when applied to men, signifies to speak Injuriously of their persons, characters, etc., and, when applied to God, it means to speak Impiously of his nature, works, etc.