Psalms 140:3

“They have sharpened their tongues like a serpent, etc.] Which Kimchi says it does before it bites. Aristotlef1877 observes, that the tip or extreme point of a serpent’s tongue is as small as a hair, and so exceeding sharp and piercing. Arama interprets this of the sharpness and cunning of the serpent; and particularly the serpent that deceived Eve, and spake cunningly to her. “For God knoweth”, etc. and may design the calumnies and detractions, which were sharp as a razor; as swords, and spears, and arrows, and as the tongue of a serpent, (<195704>Psalm 57:4 64:3); and the subtlety of false teachers, and deceitful workers; and the sharp and cutting words of wicked men against Christ and his…”

“They have sharpened their tongues like a serpent - Compare the notes at Psalms 64:3. The idea here is, that since the tongue of the serpent “seems” to be sharp, pointed, adapted to penetrate (and probably the original reference in the image was derived from that idea), the wound inflicted is by the serpent’s tongue - “as if” with a hard, penetrating point. It is now known, however, that it is by a tooth - a single tooth, made flexible for the purpose - at the root of which a small bag containing the poison is located, which is injected through an orifice in the tooth into the wound. The meaning here is, that the words spoken by such persons - by their tongues - were like the poison produced…”

“Tongues - Using words as sharp and piercing as the sting of a serpent. Psalms 140:9”

“140:3 sting like a snake . . . a viper: These creatures depict the wicked as very corrupt people (see Prov 23:32; Isa 14:29; Rom 3:13).”

“sharpened: Psa 52:2, Psa 52:3, Psa 57:4, Psa 59:7, Psa 64:3, Psa 64:4; Pro 12:18; Isa 59:3-5, Isa 59:13; Jer 9:3, Jer 9:5; Jam 3:6-8 like a serpent: Gen 3:13; Pro 23:32; Mat 12:34; Co2 11:3 adders': Psa 58:4; Rom 3:13, Rom 3:14 Psalms 140:4”