C. F. Keil and Franz Delitzsch on Proverbs 16:28

Pro 16:28 28 A man of falsehood scattereth strife,      And a backbiter separateth confidential friends.

Regarding תּהפּכות (מדבר) אישׁ, vid., Pro 2:12, and מדון ישׁלּח, Pro 6:14; the thought of 28b is found at Pro 6:19. נרגּן (with ן minusculum, which occurs thrice with the terminal Nun) is a Niphal formation from רגן, to murmur (cf. נזיד, from זיד), and denotes the whisperer, viz., the backbiter, ψίθυρος, Sir. 5:14, ψιθυριστής, susurro; the Arab. nyrj is abbreviated from it, a verbal stem of נרג (cf. Aram. norgo, an axe, Arab. naurag, a threshing-sledge = מורג) cannot be proved. Aquila is right in translating by τονθρυστής, and Theodotion by γόγγυσος, from רגן, Hiph. נרגּן, γογγύζειν. Regarding אלּוּף, confidential friend, vid., p. 82; the sing., as Pro 18:9, is used in view of the mutual relationship, and מפריד proceeds on the separation of the one, and, at the same time, of the other from it. Luther, in translating by “a slanderer makes princes disagree,” is in error, for אלּוּף, φύλαρχος, is not a generic word for prince.