“Let your word be.
‘Anything more than this
From the evil one.’”
ἔστω δὲ ὁ λόγος ὑμῶν ναὶ ναί, οὒ οὔ· τὸ δὲ περισσὸν τούτων ἐκ τοῦ πονηροῦ ἐστιν.
Matthew has Jesus say that their language should be simple (ἔστω δὲ ὁ λόγος ὑμῶν), by using only yes, yes, or no, no (ναὶ ναί, οὒ οὔ). There was not any need for anything more (τὸ δὲ περισσὸν τούτων). In fact, if there is more, it probably comes from the evil one (ἐκ τοῦ πονηροῦ ἐστιν), either the devil or Satan, who are not explicitly mentioned here. This simple speech comment was once again unique to Matthew.