Exegesis:
ho agathos anthrōpos ‘a good man’; the article has generic force. V. 45 applies to man what has been said about trees in vv. 43f.
ek tou agathou thēsaurou tēs kardias ‘from the good treasure of the (his) heart.’
thēsauros (1) ‘place where something is kept,’ ‘treasure-room’; (2) ‘that which is kept,’ ‘treasure.’ Since agathos denotes the quality of that which is kept and not the place where it is kept, interpretation (2) is preferable. tēs kardias ‘of the heart’ has locative meaning, i.e. ‘in his heart.’
propherei to agathon ‘produces what is good.’ The article to is generic. propherei is used in a literal sense, i.e. of bringing out, or, bringing to the fore (cf. Zürcher Bibel, bringt hervor, and Bible de Jérusalem, tire).
ek tou ponērou scil thēsaurou tēs kardias ‘from the evil (treasure of the heart),’ elliptic phrase.
ek gar perisseumatos kardias ‘for out of the abundance of the heart,’ gar introduces a statement of general principle.
perisseuma ‘fullness,’ ‘abundance,’ here in a concrete sense, ‘that which fills and overflows the heart.’
Translation:
The good man. If one receptor language term covers both ‘good’ and ‘beautiful,’ some qualification will be required, e.g. ‘of heart’ (Toraja-Sa’dan, Batak Toba). The same is true of “the bad man” in the next clause.
Out of the good treasure of his heart, or, ‘from the good things stored/treasured up in his heart,’ “from the store of good within himself” (New English Bible).
Out of his evil treasure. If the ellipsis has to be filled out the terms used should preserve the parallel with the preceding clause, e.g. ‘from the good things (stored/treasured up in his heart),’ ‘from the store of evil (within himself).’
Out of the abundance of the heart his mouth speaks, a literalism against which no less a translator than Luther has already declaimed. More idiomatic renderings are, ‘his mouth says only what his heart is (more than) full of’ (cf. An American Translation, Uab Meto), ‘the mouth speaks what comes from the heart, where there is a fullness of it’ (Shona 1966), ‘it is what fills (or, overflows from) the heart that comes out of the mouth’ (cf. The Four Gospels – a New Translation), ‘in our hearts arise/have-their-source all those things which come out of the mouth’ (Tzeltal). Mouth may in this context be more idiomatically rendered by ‘lips,’ ‘throat.’ In Nyanja the word for ‘mouth’ (derived from ‘to drink’) cannot be the subject of ‘to speak’; hence, ‘in his mouth there is utterance out of….’ Another language distinguishes between ‘mouth (as organ of eating)’ and ‘oral cavity (as organ of speaking),’ used here; an older version in this language employed the former term—with catastrophic results!
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.