Matthew 6:3

Σοῦ δὲ ποιοῦντος ἐλεημοσύνην, μὴ γνώτω ἡ ἀριστερά σου τί ποιεῖ ἡ δεξιά σου·

But when you give alms, do not let your left hand know what your right hand is doing,