Matthew Henry's Complete Bible Commentary

Verse 18

The tongue is death or life, poison or medicine, as it is used. 1. There are words that are cutting and killing, that are like the piercings of a sword. Opprobrious words grieve the spirits of those to whom they are spoken, and cut them to the heart. Slanders, like a sword, wound the reputation of those of whom they are uttered, and perhaps incurably. Whisperings and evil surmises, like a sword, divide and cut asunder the bounds of love and friendship, and separate those that have been dearest to each other. 2. There are words that are curing and healing: The tongue of the wise is health, closing up those wounds which the backbiting tongue had given, making all whole again, restoring peace, and accommodating matters in variance and persuading to reconciliation. Wisdom will find out proper remedies against the mischiefs that are made by detraction and evil-speaking. MHBCC 641.18