And they said unto him we can
That is, drink of Christ's cup and be baptized with his baptism which is another instance of their ignorance; for as they knew not the glorious state of things and the nature of it they desired places in so they were unacquainted with themselves; they were ignorant of their own weakness as well as of the greatness of the sufferings Christ should endure or even they should be called unto: had they had a just notion of either, they would not have expressed themselves in this manner without any mention of the grace of God or any dependence on the strength of Christ; (See Gill on Matthew 20:22).
And Jesus said unto them, ye shall indeed drink of the cup
drink of; and with the baptism that I am baptized withal shall ye be
meaning, not that they should undergo the same sufferings he did and much less for the same end and purpose: he trod the winepress alone and bore the whole punishment due to the sins of his people himself; and of them there were none with him to take a part: but that they should endure sufferings in some sort like to his for his sake as they both afterwards did; (See Gill on Matthew 20:23).