But let your word ‘Yes’ mean ‘Yes,’ and ‘No’ mean ‘No.’ For anything beyond that is of evil. (Mat 5:37)
ἔστω δὲ ὁ λόγος ὑμῶν ναὶ ναί, οὒ οὔ· τὸ δὲ περισσὸν τούτων ἐκ τοῦ πονηροῦ ἐστιν.
Sit autem sermo vester, est, est: non, non: quod autem his abundantius est, a malo est.