See the notes at Matthew 18:1-5. Compare Mark 9:33-38.

There arose a reasoning - Εισηλθε δε διαλογισμος, A dialogue took place - one inquired, and another answered, and so on. See this subject explained on Matthew 18:1 (note), etc.

Then there arose a reasoning among them,.... The Vulgate Latin, Syriac, and Arabic versions read, "a thought entered into them"; suggested very likely by Satan, which broke out into words, and issued in a warm dispute among them; and this was in the way, as they were travelling from Caesarea Philippi, to Capernaum; see Mark 9:33.

Which of them should be greatest; that is, "in the kingdom of heaven", as in Matthew 18:1 in the kingdom of the Messiah, which they expected would be a temporal one: wherefore the dispute was not about degrees in glory, nor in grace; nor who should be the greatest apostle and preacher of the Gospel; but who should be prime minister to the king Messiah, when he should set up his monarchy in all its grandeur and glory.

A reasoning (διαλογισμὸς)

A debate or discussion. See on Luke 24:38, and James 1:22; James 2:4.

{9} Then there arose a reasoning among them, which of them should be greatest.

(9) Ambition results in dishonour, but the result of modest obedience is glory.

9:46-50 Which of them should be greatest. See notes on Mt 18:1-6 Mr 9:33-50. For notes on the question of John and the Lord's answer, see Mark as above.

9:46 And there arose a reasoning among them - This kind of reasoning always arose at the most improper times that could be imagined.

Lu 9:46-48. Strife among the Twelve Who Should Be Greatest-John Rebuked for Exclusiveness.

46-48. (See on [1614]Mt 18:1-5).

9:43-50 This prediction of Christ's sufferings was plain enough, but the disciples would not understand it, because it agreed not with their notions. A little child is the emblem by which Christ teaches us simplicity and humility. What greater honour can any man attain to in this world, than to be received by men as a messenger of God and Christ; and to have God and Christ own themselves received and welcomed in him! If ever any society of Christians in this world, had reason to silence those not of their own communion, the twelve disciples at this time had; yet Christ warned them not to do the like again. Those may be found faithful followers of Christ, and may be accepted of him, who do not follow with us.