That when the cup of the Prophet cracked, he mended the crack with a silver chain
Authentic hadithعن أنس بن مالك رضي الله عنه أن قَدَحَ النبي صلى الله عليه وسلم انْكَسَرَ، فاتَّخَذَ مكان الشَّعْبِ سِلْسِلَةً من فِضة.
Anas ibn Mālik (may Allah be pleased with him) reported that when the cup of the Prophet cracked, he mended the crack with a silver chain.
Explanation
The Prophet (may Allah's peace and blessings be upon him) had a glass to drink water in. The cup cracked, so the Prophet (may Allah's peace and blessings be upon him) mended it with a silver chain, i.e. He took a piece of silver and joined the two sides of the crack.
Source · Narrated by Bukhari
From the Hadith Encyclopedia (hadeethenc.com).