James and John wanted the highest places, but they did not understand the road that led there. Jesus first said, "Ye know not what ye ask," which Barnes explains as "You do not know the nature of your request, nor what would be involved in it." They imagined honor and happiness; it would require suffering. His question turns their eyes from thrones to His cup. Gill notes that Jesus speaks to the two sons, and that it would have been fitting, after hearing of His coming sufferings, if they had asked themselves this very question.

They answered, "We are able" (Matthew 20:22). Jesus told them, "Ye shall drink indeed of my cup, and be baptized with the baptism that I am baptized with," but said the places at His right and left were "not mine to give, but it shall be given to them for whom it is prepared of my Father" (Matthew 20:23). Barnes notes that the prophecy came true: James was killed "with the sword" (Acts 12:2), and John was exiled on Patmos "for the testimony of Jesus Christ" (Revelation 1:9).

In Scripture, drinking a cup often pictures receiving suffering or judgment from God's hand. Barnes cites Psalm 75:8 and Isaiah 51:17, and connects it with Jesus' words at His arrest, "the cup which my Father hath given me, shall I not drink it?" (John 18:11). Baptism here pictures being overwhelmed by sorrow like floods of water; Barnes cites Psalm 69:2 and Isaiah 43:2.

The KJV, following the Textus Receptus, includes "and to be baptized with the baptism that I am baptized with." Most modern critical Greek texts omit these words in Matthew, so the ESV does not have them. Mark's account also includes the baptism saying (Mark 10:38).

Jesus' question shows that the way to glory with Him runs through suffering with Him. He had just foretold His death (Matthew 20:18-19), and He would speak of the same cup in Gethsemane (Matthew 26:39). Matthew Henry calls it "a bitter cup," yet "a cup in the hand of a Father."

The brothers' "We are able" was sincere but untested. Gill says they answered without "considering the nature of these sufferings, and their own weakness." Henry observes, "Those are commonly most confident, who are least acquainted with the cross." Still, Jesus did not reject them. He told them they would indeed share His cup (Matthew 20:23), and history bore it out. Barnes adds that Jesus does give rewards, but only to those for whom they are prepared by the Father. He notes that some words in the KJV here were added by the translators, and reads it, "not mine to give, except to those for whom it is prepared of my Father."