do one a bad turn
From LSJ
Τὸ μανθάνειν δ' ἥδιστον εὖ λέγοντος, εἰ κέρδος λέγοι → It is the sweetest thing to learn from one speaking well, if they speak profitably
English > Greek (Woodhouse Extra)
κακῶς ποιεῖ, κακῶς ποιεῖν, κακῶς δρᾶν
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