Albert Barnes Commentary Matthew 18:1

"In that hour came the disciples unto Jesus, saying, Who then is greatest in the kingdom of heaven?" — Matthew 18:1 (ASV)

Who is the greatest in the kingdom of heaven? By the kingdom of heaven they meant the kingdom which they supposed he was about to set up—his kingdom as the Messiah. They asked the question because they supposed, in accordance with the common expectation of the Jews, that he was about to set up a temporal kingdom of great splendor; and they wished to know who should have the principal offices and posts of honor and profit.

This was among them a frequent subject of inquiry and controversy. Mark 9:34 informs us that they had had a dispute on this subject on the way. Jesus, he says, inquired of them what they had been disputing about. Luke 9:47 says that Jesus perceived the thought of their heart;—an act implying omniscience, for none can search the heart but God (Jeremiah 17:10).

The disciples, conscious that the subject of their dispute was known, requested Jesus to decide it (Matthew 18:1). They were at first silent through shame (Mark 9:34), but perceiving that the subject of their dispute was known, they came, as Matthew states, and referred the matter to him for his opinion.