John Chrysostom — as excerpted in the Catena Aurea on John 2:23-25

“(Hom. xxv. 1) Or it means that He did not place confidence in them, as perfect disciples, and did not, as if they were brethren of confirmed faith, commit to them all His doctrines, for He did not attend to their outward words, but entered into their hearts, and well knew how short-lived was their zeal1. Because He knew all men, and needed not that any should testify of man, for He knew what was in man. To know what is in man’s heart, is in the power of God alone, who fashioned the heart. He does not want witnesses, to inform Him of that mind, which was of His own fashioning.”