Matthew 5:36

μήτε ἐν τῇ κεφαλῇ σου ὀμόσῃς ὅτι οὐ δύνασαι μίαν τρίχα λευκὴν ποιῆσαι ἢ μέλαιναν

mēte en tē kephalē sou omosēs hoti ou dynasai mian tricha leukēn poiēsai ē melainan

neither in the head of You shall you swear - not you are able one hair white to do or black