John Chrysostom

Wherefore He said also, "But I say unto you, That in this place is one greater than the temple." Nevertheless, great as the sayings were which they heard, they made no reply, for the salvation of men was not their object.

Homily on the Gospel of Matthew 39 ↗

Jerome

But I tell you that here is a greater temple. Here, is not a pronoun, but an adverb of place; that the place, which holds the Lord of the temple, is greater than the temple.

Commentary on Matthew ↗

Hilary of Poitiers

Christ also reminded them of another prophecy so that they might learn that all things that were spoken of previously were accomplished in him through the law, that the priests in the temple broke the sabbath without offense, clearly revealing that Jesus himself was the temple. In him salvation was given to the Gentiles through the teaching of the apostles, while the people who were bound by the law wandered about faithlessly, so that he himself might be greater than the sabbath. Evangelical faith lived in Christ transcends the law.

Commentary on Matthew 12.4 ↗

Thomas Aquinas

I tell you this, that something greater than the temple is here. That something greater than the temple is here is clear, because his body is a temple. Likewise it should be noted that in the first example he does not claim that it is without sin. In the second he states that if one breaks the Sabbath out of necessity, it is not on that account entirely free of sin; but it is, if it is done on account of God.

Commentary on Matthew ↗