ὑπὸ σκότῳ

From LSJ

λέγεις, ἃ δὲ λέγεις ἕνεκα τοῦ λαβεῖν λέγεις → you speak, but you say what you say for the sake of gain (Menander, fr. 776)

Source

Dutch (Woordenboekgrieks.nl)

in duisternis, in het geheim