Albert Barnes Commentary Matthew 20:23

"He saith unto them, My cup indeed ye shall drink: but to sit on my right hand, and on [my] left hand, is not mine to give; but [it is for them] for whom it hath been prepared of my Father." — Matthew 20:23 (ASV)

Ye shall drink indeed of my cup, etc. You are truly attached to me, you will follow me, and you will share in my afflictions, and will suffer as I shall. This was fulfilled. James was killed with the sword by Herod (Acts 12:2). John lived many years. But he accompanied the Savior through his sufferings, and was himself banished to Patmos, a solitary island, for the testimony of Jesus Christ—a companion of others in tribulation (Revelation 1:9).

Is not mine to give, etc. The translation of this passage evidently does not express the sense of the original. The translation expresses the idea that Jesus has nothing to do with bestowing rewards on his followers. This is contrary to the uniform testimony of the Scriptures (Matthew 25:31–40; John 5:22–30).

The correct translation of the passage would be, "To sit on my right hand and on my left is not mine to give, except to those for whom it is prepared by my Father." The passage thus declares that Christ would give rewards to his followers, but only to those who are entitled to them according to the purpose of his Father.

Much as he might be attached to these two disciples, yet he could not bestow any such special favors on them outside the regular course of rewards. Rewards were prepared for his followers, and in due time they should be bestowed. He would bestow them as they had been provided from eternity by God the Father.

The correct sense is seen by leaving out that part of the verse in italics; and this is one of the places in the Bible where the sense has been obscured or perverted by the introduction of words that have nothing to correspond with them in the original. See a similar instance in 1 John 2:23.