Exegesis:

legei autō ‘he said to him’; change of subject without indication.

ek tou stomatos sou krinō se lit. ‘out of your own mouth I condemn you,’ i.e. on the basis of your own words, cf. Good News Translation. krinō may be interpreted as present (so GOOD NEWS BIBLE), or as future (so Nestle), depending on the accentuation in Greek. The latter is preferable. krinō is a judicial term, here used in a non-judicial situation meaning either ‘to condemn,’ or ‘to judge,’ preferably the former.

Translation:

He said to him, or to specify the reference, ‘the master (or, king) said/replied.’

I will condemn you out of your own mouth, or, “by your own words” (New English Bible), ‘in accordance with what you yourself just said,’ ‘by what comes-out of your mouth, or, lips’ (cf. Kituba, Toraja-Sa’dan); or recasting the sentence structure, “I will use your own words to condemn you” (Good News Translation), ‘you yourself are saying with your own mouth what you will be judged by’ (Tzeltal); or again, taking a non-personal subject, ‘the word you uttered condemns you’ (Ekari, similarly Shona 1966). For condemn see on 6.37.

You wicked servant may have to be transposed to the beginning of the discourse, and/or rendered as a statement.

You knew … sow?, a rhetorical question that may have to become a statement, e.g. ‘you said that you knew … sow.’

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.