Sahih Bukhari Volume 7, Book 69, Hadith Number 542.

Narrated By ‘Asim al-Ahwal : I saw the drinking bowl of the Prophet with Anas bin Malik, and it had been broken, and he had mended it with silver plates. That drinking bowl was quite wide and made of Nadar wood, Anas said, “I gave water to the Prophet in that bowl more than so-and-so (for a long period).” Ibn Sirin said: Around that bowl there was an iron ring, and Anas wanted to replace it with a silver or gold ring, but Abu Talha said to him, “Do not change a thing that Allah’s Apostle has made.” So Anas left it as it was.