Albert Barnes on Matthew 18:1-6

See also Mk 9:33-41, Lk 9:46-60. 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 splendour; and they wished to know who should have the principal offices and posts of honour and profit. This was among them a frequent subject of inquiry and controversy. Mk 9:34 informs us that they had had a dispute on this subject in the way. Jesus, he says, inquired of them what they had been disputing about. Lk 9:47 says, that Jesus perceived the thought of their heart;--an act implying omniscience, for none can search the heart but God, Jer 17:10. The disciples, conscious that the subject of their dispute was known, requested Jesus to decide it, Mt 18:1. They were at first silent through shame, Mk 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.

(u) "At the same" Mk 9:33, Lk 9:46, 22:24