By thy words thou shalt be justified ... - That is, “words” are the indication of the true principles of the heart; by “words” the heart shall be known, as the tree is by its fruit. If they are true, proper, chaste, instructive, pious, they will prove that the heart is right. If false, envious, malignant, and impious, they will prove that the heart is wrong, and will therefore be among the causes of condemnation. It is not meant that words will be the only thing that will condemn man, but that they will be an important part of the things for which he shall be condemned. See James 3:3-12.
Related Commentaries of Matthew 12:37
Matthew 12:37
37 For by thy words thou shalt be justified, and by thy words thou shalt be condemned.