Jesus wanted to bring a hidden argument into the open. He had just told them, "The Son of man is delivered into the hands of men, and they shall kill him" (Mark 9:31). But "they understood not that saying, and were afraid to ask him" (Mark 9:32). Instead of asking Him, they argued with each other on the road. Luke says Jesus already knew "the thought of their heart" (Luke 9:47), and Gill says Christ asked not because He did not know, but to deal with the matter openly. Gill describes their argument as being over who should have "the greatest place of authority, honour, and dignity, in the temporal kingdom of the Messiah."

The disciples said nothing: "But they held their peace: for by the way they had disputed among themselves, who should be the greatest" (Mark 9:34). Jesus then sat down, called the twelve, and said, "If any man desire to be first, the same shall be last of all, and servant of all" (Mark 9:35). He set a child in the midst of them, took him in His arms, and said that whoever receives one such child in His name receives Him, and receives "him that sent me" (Mark 9:36-37).

The word translated "disputed" is dialogizomai, which Thayer defines as "to reason, revolve in one's mind, deliberate." Here it is in a tense that pictures an ongoing discussion, carried on along the road.

The disciples were not arguing about a small thing. Barnes explains that they expected Jesus to set up "a temporal kingdom of great splendor," and wanted to know who would hold "the principal offices and posts of honor and profit." Gill adds that this is part of why they could not understand Jesus' words about His death: they could not fit them with the notions they had of the Messiah "setting up a temporal kingdom on earth" (Mark 9:32). Matthew records the same concern as a question the disciples brought to Jesus: "Who is the greatest in the kingdom of heaven?" (Matthew 18:1).

Jesus knew what they had argued about, yet He asked. His question gave them room to bring their hidden thoughts into the light, and it set up His teaching on what greatness really is. Matthew Henry writes, "We shall be called to account about our discourses, and to account for our disputes, especially about being greater than others."

The contrast is striking. On the same road where Jesus spoke of being delivered into the hands of men, His followers argued about rank. Jesus answered by turning greatness upside down: the first is "last of all, and servant of all" (Mark 9:35). The disciples did not learn this all at once. The same desire comes back with James and John (Mark 10:35-41), and Jesus teaches it again, pointing to Himself: "the Son of man came not to be ministered unto, but to minister" (Mark 10:45).