John Chrysostom

"Thou therefore which teachest another, teachest thou not thyself?" But there he frames his speech with more of sharpness, here with more of gentleness. For he does not say, However on this score thou deservest greater punishment, because though entrusted with so great things thou hast not made a good use of any of them, but he carries his discourse on by way of question, turning them on themselves, and saying, "Thou that teachest another, teachest thou not thyself?" And here I would have you look at the discretion of Paul in another …

Homily on Romans 6 ↗

Theophylact of Ohrid

He presents his thought in the form of a question, shaming those who boasted that they were teachers.

Commentary on Romans ↗

Desert Fathers

Poemen also said, 'Teach your heart to follow what your tongue is saying to others.' He also said, 'Men try to appear excellent in preaching but they are less excellent in practising what they preach.'

The Desert Fathers, Sayings of the Early Christian Monks ↗

Thomas Aquinas

Then when he says you who teaches another, he indicates some of their failings. First, failings toward themselves, when he says you who teaches another, by directing them to the good, teaches not yourself. This can be taken as a question asked with an overtone of indignation or with an overtone of mildness which, nevertheless, suggests wickedness on their part, as it does in Job: behold, you have instructed many . . . the scourge has now touched you and you faint (Job 4:3–5). Second, their failings toward their neighbor. …

Commentary on Romans ↗