[21:23] 1 sn “Mouth” and “tongue” are metonymies of cause, signifying what one says (cf. NCV, TEV, CEV).
[21:23] 2 tn This part could also be translated “keeps himself” (so NIV), for נֶפֶשׁ (nefesh) often simply means “the whole person.” The participle שֹׁמֵר (shomer) is repeated from the first line in the parallelism – to guard what is said is to guard against difficulty.
[21:23] 3 sn The “troubles” (צָרוֹת, tsarot) here could refer to social and legal difficulties into which careless talk might bring someone (e.g., 13:3; 18:21). The word means “a strait, a bind, difficulty.” Careless and free talking could get the person into a tight spot.
