John Chrysostom

What unbelief, saith some one, is here? They exhort Him to work miracles. It is great deed; for of unbelief come their words, and their insolence, and their unseasonable freedom of speech. For they thought, that owing to their relationship, it was lawful for them to address Him boldly. And their request seems forsooth to be that of friends, but the words were those of great maliciousness. …

Homily on the Gospel of John 48 ↗

Theophylact of Ohrid

His brothers, that is, the sons of Joseph, accuse Him of two dispositions: cowardice and love of glory. Therefore they also say: "no one does anything in secret" — this is a sign of cowardice, and "and seeks himself to be known" — this is a sign of love of glory. "If," they say, "You do such works, then show Yourself to the world." By this they are saying, as it were: "We do not understand Your conduct in a favorable light. …

Commentary on John ↗

Thomas Aquinas

They reveal that they themselves are suspicious, and first of all remark on Christ's fear, saying: Surely, no one works in secret. As if to say: You say that you are performing miracles. But you are doing them secretly because of fear; otherwise you would go to Jerusalem and do them before the people. Nevertheless, our Lord says below: "I have said nothing secretly" (below 18:20). Secondly, they refer to his love of glory, saying: if he wants to be publicly renowned. …

Commentary on John ↗

Bonaventure

And they add a third reason, namely the manifestation of his name. "For no one does anything in secret and himself seeks to be known openly," through that work, namely; such men had not yet departed from the mindset of hypocrites, of whom it is said in Matthew twenty-three: "They do all their works to be seen by men." Therefore they said: "If you do these things, manifest yourself to the world," that is, if the miracles you perform are true as from God, manifest yourself. They say this doubting, and the Evangelist gives the reason.

Commentary on John, Chapter 7 ↗