Matthew 20:23

And he saith unto them, ye shall drink indeed of my cup
Not of the selfsame, but of what was like unto it; meaning, that they should endure much persecution for his name's sake, as all that will live godly in Christ Jesus must expect in one shape or another. Thus James, who was one of these persons, was slain with the sword by Herod; John, the other, was imprisoned, and beaten by the order of the Jewish sanhedrim, was banished into the isle of Patmos by Domitian; and, some say, was cast into a cauldron of boiling oil, though saved in it: so that these words seem to be a prophecy of what they should suffer for Christ, instead of enjoying places of worldly honour and profit under him, they were seeking for.

And be baptized with the baptism that I am baptized with:
this clause is here, and in the former verse, omitted by the Vulgate Latin, and Ethiopic versions, and in some Greek copies, and is thought to be transcribed hither out of Mark's Gospel; but the Syriac, Arabic, and Persic versions have it, and so has Munster's Hebrew Gospel, and it appears in many Greek copies. James, being bathed in his own blood, when killed with the sword, and John being cast into a vessel of scalding oil, these are fitly expressed by a baptism.

But to sit on my right hand, and on my left, is not mine, to give;
in the sense in which they asked it, since he was no temporal prince; nor was his kingdom of this world; nor had he any such external favours, or worldly honours: and as to the true and spiritual sense of such a phrase, it was not a point to be fixed now by him, as man, and according to his own will; as who should reign with him in the kingdom of heaven, who should sit down on the same throne with him, and enjoy all the glories and happiness of the world to come; and though, as mediator, all this glory was given to him, and he had it in his hands to give to others, yet to none

but
those for whom,
says he, it is prepared of my Father:
for this is the true reading and sense of the last clause; signifying, that eternal life, or the heavenly glory, is a kingdom prepared by his Father, from the foundation of the world, and not for anybody, and every person, but for some only, according to his Father's sovereign will and pleasure; and that this is an affair that was fixed by him, in his eternal counsels and purposes, and in the covenant of his grace, and not to be adjusted now; nor was the designation of it to be, nor will the distribution of it be according to the merits of men, but the free grace of God; and though he, as mediator, was appointed to bestow both grace and glory on men, yet only on those the Father had given to him, for whom grace was laid up in him, and glory prepared.