Albert Barnes on Matthew 9:3

This man blasphemeth. The word blaspheme originally means to speak evil of any one, to injure by words, to blame unjustly. When applied to God, it means to speak of him unjustly, to ascribe to him acts and attributes which he does not possess, or to speak impiously or profanely. It also means to say or do anything by which his name or honour is insulted, or which conveys an impress on unfavourable to God. It means, also, to attempt to do or say a thing which belongs to him alone, or which he only can do. This is its meaning here. Christ was charged with saying a thing in his own name, or attempting to do a thing which properly belonged to God; thus assuming the place of God, and doing him injury, as the scribes supposed, by an invasion of his prerogatives. "None," said they, (see Mark and Luke,) "can forgive sins but God only" In this they reasoned correctly. See Is 43:25, 44:22. None of the prophets had this power; and by saying that he forgave sins, Jesus was understood to affirm that he was Divine; and as he proved this by working a miracle expressly to confirm the claim, it follows that he is Divine, or equal with the Father.