a silver/smooth tongue

silver tongue

Oratory skills that are particularly eloquent, artful, seductive, and/or persuasive. He might not have much experience in politics, but his silver tongue is bound to win over a great deal of voters.
See also: silver, tongue
Farlex Dictionary of Idioms.

a ˌsilver/ˌsmooth ˈtongue

the ability to talk in a very pleasing and polite way, to make people do what you want: It was his silver tongue that got him the job. ▶ ˌsilver-ˈtongued, ˌsmooth-ˈtongued adj.: smooth-tongued salesmen
See also: silver, smooth, tongue
Farlex Partner Idioms Dictionary
See also:
  • silver tongue
  • have a silver tongue
  • silver-tongued
  • silver-tongued orator
  • wagonload
  • (as) artful as a wagonload of monkeys
  • artful
  • as artful as a wagonload of monkeys
  • honey-mouthed
  • on the tip of (one's) tongue