Exegesis:
pas ho erchomenos ‘every one who comes.’
akouōn mou tōn logōn kai poiōn autous ‘hears my words and does them,’ i.e. puts the words into practise (cf. Phillips), or acts according to them (cf. The Four Gospels – a New Translation, An American Translation). As contrasted with the aorist tense of akousas and poiēsas in v. 49 the present tense of the participles in this verse refers to an abiding attitude, whereas in v. 49 the reference is to a decision that has been made.
hupodeixō humin tini estin homoios ‘I will show you whom he is like.’ Syntactically the subject of estin is pas ho erchomenos etc. After introducing this subject at length in the nominative the writer as it were interrupts himself and begins anew with hupodeixō ‘I will show,’ and takes up pas ho erchomenos in the clause which is dependent upon hupodeixō. Several translations render tini estin homoios as ‘what he is like’ (cf. Revised Standard Version) but as v. 48 shows tini is to be understood as masculine in gender, “whom he is like” (An American Translation).
Translation:
Without interruption the sentence may run like this, ‘I will show you whom everyone is like who comes … and does…,’ or to avoid subordination, ‘persons come, … and hear … and do … Whom are they like? I will show you that.’
My words, or, ‘what I say (to him), or, tell (him)’; cf. also “this teaching of mine” (An American Translation), “what I have to say” (Phillips).
Does them. The verb may have to be rendered less generically, e.g. ‘obeys (cf. on 2.51) them,’ or, ‘keeps/observes them.’
I will show you what (preferably, whom) he is like, or, ‘who he is’ (Sranan Tongo, where a literal rendering would suggest outward resemblance only). To show, or, ‘to cause-to-see’; or, since the seeing is with the eye of the mind, ‘to explain,’ ‘to make clear,’ “to give an idea” (The Four Gospels – a New Translation).
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.