Augustine of Hippo
Catena Aurea · Johannesevangelium 2
Now when he was in Jerusalem at the passover, in the feast day, many believed in his name, when they saw the miracles which he did. But Jesus did not commit himself unto them, because he knew all men. And needed not that any should testify of man: for he knew what was in man.
(Tr. xi. in Joan. c. 2. 3) What meaneth this, Many believed in His Name—but Jesus did not commit Himself unto them? Was it that they did not believe in Him, but only pretended that they did? In that case the Evangelist would not have said, Many believed in His Name. Wonderful this, and strange, that men should trust Christ, and Christ trusts not Himself to men; especially considering that He was the Son of God, and suffered voluntarily, or else need not have suffered at all. Yet such are all catechumens. If we say to a catechumen, Believest thou in Christ? he answers, I do believe, and crosses himself. If we ask him, Dost thou eat the flesh of the Son of man? he knows not what we sayk, for Jesus has not committed Himself to him.