Cyril of Alexandria

They take upon themselves to slander a man worthy of all admiration. They say that he who mortifies the law of sin which is in his members hath a devil.

Catena Aurea by Aquinas ↗

Bede

For John the Baptist came neither eating bread nor drinking wine, and you say, "He has a demon." The Son of Man has come eating and drinking, and you say, "Behold, a glutton, and a wine-drinker, a friend of tax collectors and sinners." Just as (he says) then, so now you will not accept either path of salvation. For when he says, "We mourned, and you did not weep," it pertains to John, whose abstinence from food and drink signified the mourning of repentance. …

On the Gospel of Luke ↗

Bonaventure

Third, as to the mark of detraction in speech, by which they turn good into evil, it is said: John the Baptist came neither eating bread nor drinking wine, and thus in the way of severity and justice, as is said in Matthew 21: "John came to you in the way of justice." Whence, because he came with the austerity of penance, he came as one lamenting and groaning for the salvation of the people, according to that passage of Daniel 10: "I Daniel mourned for three weeks of days; I did not eat desirable bread, and flesh and wine did not …

Commentary on Luke, Chapter 7 ↗