口说无凭，事实为证

 (Kǒu shuō wú píng, shìshí wéi zhèng)

Have you ever heard grand promises that vanished into thin air? A friend swears, "I’ll help you tomorrow!" but never shows up. A salesperson raves, "This product is amazing!" only for you to discover it’s useless. When words fall short, an ancient Chinese proverb reveals the truth:
口说无凭，事实为证 (Kǒu shuō wú píng, shìshí wéi zhèng).