John Chrysostom

Upon their murmuring, then, and saying, "This man blasphemeth; who can forgive sins but God only?" let us see what He saith. Did He indeed take away the suspicion? And yet if He were not equal, He should have said, "Why fix upon me a notion which is not convenient? I am far from this power." But now hath He said none of these things, but quite the contrary He hath both affirmed and ratified, as well by His own voice, as by the performance of the miracle. …

Homily on the Gospel of Matthew 29 ↗

Theophylact of Ohrid

"And, behold, certain of the scribes said within themselves, This man blasphemeth. And Jesus knowing their thoughts said, Wherefore think ye evil in your hearts? For which is easier to say, Thy sins be forgiven thee; or to say, Arise, and walk?" By knowing their thoughts, Jesus shows that He is God. He rebukes them by saying, "You think that I am blaspheming by promising to forgive sins, which is a great thing, and that I resort to this because it is something which can not be verified. …

Commentary on Matthew ↗

Jerome

And behold, some of the scribes said to themselves: He blasphemes. And when Jesus saw their thoughts, he said: Why do you think evil in your hearts? We read in the Prophet, saying God: I am the one who blots out your iniquities (Isaiah 43:25). Therefore, the scribes, because they thought he was a man and did not understand the words of God, accuse him of blasphemy. …

Commentary on Matthew ↗

Thomas Aquinas

Then he mentions the complaint against the favor. He says, therefore, Some of the scribes said within themselves, "This man is blaspheming." Why? Because they saw the man and did not see God. But only God can forgive sins; therefore, they called him a blasphemer: Job (34:18): "Who says to a king, 'Worthless one', and to nobles, 'Wicked man'." But Jesus, knowing their thoughts said, "Why do you think evil in your hearts?" Here he refutes them in three ways: by his knowledge, by a word and by a deed. …

Commentary on Matthew ↗