John Gill Bible Commentary

And they understood none of these things,.... "Not one of them", as the Syriac and Persic versions render it; every article of his sufferings and death were unintelligible by them; they knew not how to understand him in any one point: or how to reconcile these things to the notions they had entertained of the temporal grandeur, and glory, of the Messiah, and his kingdom; and which shows their great ignorance of the prophecies of the Old Testament concerning these things. And this saying, or "thing"; for it answers to the Hebrew word which signifies any affair, or matter, as well as a word, or saying: and so here, the whole of this affair was hid from them; unless it should have a peculiar regard to that part of it, which expresses his resurrection from the dead; see Mar 9:10 or the delivery of him to the Gentiles, Luk 9:44 neither knew they the things which were spoken; the meaning of them. The Ethiopic version leaves out this, and puts the former clause, by way of question, "and he said unto them, and is this saying hid from you?"