Now are we sure that thou knowest all things,.... Not only all men, but all things, even the secrets of men's hearts, of which the apostles had now a convincing proof; for whereas Christ had delivered some expressions, Joh 16:16; which they did not understand, and were desirous to ask him the meaning of, Joh 16:19; which he knowing, being God omniscient, prevents their putting the question to him, and enters upon a discourse, in which he so clearly explained what they wanted to be informed of, without their asking him, that they were fully assured that he must know all things;and, as they add,needest not that any man should ask thee: the meaning is, that should Christ deliver anything not so intelligible to any of his audience, and they were desirous of knowing the sense of it, there would be no need of putting the question in form to him, since he is privy to the first motion of desire rising up in the mind; and can, and will, if he thinks fit, explain himself on such an head, to the satisfaction of the person, without ever asking him; at least there is no need of putting the question to make him acquainted with his desire, this being before known unto him.
By this we believe that thou camest forth from God; was the true Messiah, and had his mission and commission from God, as such; doubtless they believed this before, but this instance of Christ's omniscience was a strengthening proof of it.
So Nathanael, by Christ's saying to him, that before Philip called him, and when he was under the fig tree, he saw him when he thought no eye did but an omniscient one; it laid him under such full convictions of him, as at once to acknowledge him the Son of God, the King of Israel.
This is one of the signs and characters of the Messiah with the Jews, that he should have a discerning spirit of men and things, according to Isa 11:3 . T. Bab. Sanhedrin, fol. 93.