解鈴還須繫鈴人〔-铃还须系铃-〕 gaai² ling⁴ waan⁴ seoi¹ hai⁶ ling⁴ jan⁴ {jiě líng hái xū xì líng rén}

1. lit. whoever hung the bell on the tiger's neck must untie it (idiom)
2. fig. whoever started the trouble should end it