John Chrysostom
From this it is clear how knowledgeable Apollos was in the Scriptures. He strongly stopped the mouths of the Jews. This is what "refuted" means.
He encouraged the believers and strengthened them in the faith. Paul spoke of him in the Epistle: "As for brother Apollos" (1 Cor 16:12).
In that he reproved them publicly, his boldness appeared. In that he did so strongly, power was revealed. In that he proved it from the divine Scriptures, experience was expressed.
For boldness by itself brings no profit if there is no power, nor does power without boldness. Therefore Paul did not leave Aquila in Ephesus in vain.
Perhaps the Spirit arranged this for Apollos, so that he might appear in Corinth with greater power.
But why did they do nothing against him, while they attacked Paul? They knew that this man was the head, or that his name was great.