And how it is written - Rather, as also it is written. Instead of και πως, And How it is written, I read καθως, As Also it is written of the Son of man, etc. This reading is supported by AKM, seventeen others, the later Syriac in the margin, Slavonic and Armenian. Some think the propriety of adopting this reading is self-evident.

And he answered, and told them,.... Allowing that their observation was right, and that this was the sense of the Scribes, and that there was something of truth in it, when rightly understood:
Elias verily cometh first, and restoreth all things: See Gill on Matthew 17:11;
and how it is written of the son of man, that he must suffer many things, and be set at nought. The sense of Christ is, that John the Baptist, whom he means by Elias, comes first, and restores all things: and among the rest of the things he sets right, this is one, and not of the least; namely, that he gives the true sense of such passages of the sacred writings, which related to the contemptuous usage, rejection, and sufferings of the Messiah; as that in these he was the Lamb of God typified in the sacrifices of the law, who by his sufferings and death takes away the sin, of the world; and therefore he exhorted and directed those to whom he ministered, to look unto him, and believe in him; see John 1:29.

Elijah verily coming first restoreth all things: and how it is written - That is, And he told them how it is written - As if he had said, Elijah's coming is not inconsistent with my suffering. He is come: yet I shall suffer. The first part of the verse answers their question concerning Elijah; the second refutes their error concerning the Messiah's continuing for ever.