Exegesis:

apokritheis ‘answering,’ cf. on 1.60.

epistata ‘master,’ cf. on 5.5.

eidomen tina en tō onomati sou ekballonta daimonia ‘we saw somebody casting out demons in your name,’ i.e. “using your name” (The Four Gospels – a New Translation). en tō onomati sou recalls epi tō onomati mou in v. 48.

kai ekōluomen auton ‘and we tried to stop him’; conative imperfect.

hoti ouk akolouthei meth’ hēmōn, scil soi ‘because he does not follow (you) with us,’ i.e. he is not together with us in following you.

Translation:

John answered, lit. ‘answering John said,’ or, ‘thereupon John said,’ “here, J. said to him” (The Four Gospels – a New Translation), ‘then J. broke in’ (Javanese).

We … we are best taken as exclusive (e.g. in Tae’).

In your name has instrumental force; hence, “with your name” (An American Translation), ‘by-means-of your name’ (Balinese, similarly Sranan Tongo, lit. taking your name). Other useful, more or less descriptive renderings are, ‘borrowing your name’ (Tae’ 1933), ‘mentioning your name’ (Sundanese), ‘relying upon your name’ (Batak Toba).

Forbade him, or, ‘tried to stop/check/prevent him’; or, “told him not to do so” (An American Translation), ‘said, “Don’t do that” ’ (Navajo).

Because. Enga conveys the causal idea by using ‘seeing that.’

He does not follow with us, or, ‘he does not follow you as we do,’ ‘he is not your follower as we are’ (the pronoun ‘we’ having exclusive force), ‘he does not join (us) in following you’ (Bahasa Indonesia, Balinese); or, ‘he is not with us, or, one of us’ (cf. New English Bible, Southern Subanen), ‘us’ having inclusive force, since the speaker himself is one of Jesus’ followers. For to follow see on 5.11.

Quoted with permission from Reiling, J. and Swellengrebel, J.L. A Handbook on the Gospel of Luke. (UBS Handbook Series). New York: UBS, 1971. For this and other handbooks for translators see here . Make sure to also consult the Handbook on the Gospel of Mark for parallel or similar verses.