A "silver tongue" implies one with a tendency to be eloquent and persuasive in speaking.

Who is called man with silver tongue?

It was 1794. The Seminoles hated slavery and helped runaway Negroes whenever they could. The Seminoles called Luther “the boy with the silver tongue” because of all the languages he could speak, including most of the Indian languages.

What does it mean to have a golden tongue?

: gifted with superior powers of utterance or persuasion : eloquent.