We forbade him - See this subject considered on Mark 9:38 (note), etc.

And John answered and said, Master,.... The Syriac and Persic versions read, "our Master":

we saw one casting out devils in thy name, and we forbad him; See Gill on Mark 9:38.

Because he followeth not with us; the Syriac, Persic, and Ethiopic versions read, "because he followeth not thee with us"; did not join in company with them, and follow Christ along with them, and as they did.

{10} And John answered and said, Master, we saw one casting out devils in thy name; and we forbad him, because he followeth not with us.

(10) Extraordinary things are neither rashly to be allowed nor condemned.

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.

9:49 Mr 9:38.

49, 50. John answered, &c.-The link of connection here with the foregoing context lies in the words "in My name" (Lu 9:48). "Oh, as to that," said John, young, warm, but not sufficiently apprehending Christ's teaching in these things, "we saw one casting out devils in Thy name, and we forbade him: Were we wrong?" "Ye were wrong." "But we did because he followeth not us,'" "No matter. For (1) There is no man which shall do a miracle in My name that can lightly [soon] speak evil of Me' [Mr 9:39]. And (2) If such a person cannot be supposed to be 'against us,' you are to consider him 'for us.'" Two principles of immense importance. Christ does not say this man should not have followed "with them," but simply teaches how he was to be regarded though he did not-as a reverer of His name and a promoter of His cause. Surely this condemns not only those horrible attempts by force to shut up all within one visible pale of discipleship, which have deluged Christendom with blood in Christ's name, but the same spirit in its milder form of proud ecclesiastic scowl upon all who "after the form which they call a sect (as the word signifies, Ac 24:14), do so worship the God of their fathers." Visible unity in Christ's Church is devoutly to be sought, but this is not the way to it. See the noble spirit of Moses (Nu 11:24-29).

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.