万箭穿心必定百毒不侵
[wàn jiàn chuān xīn bì dìng băi dú bù qīn]
'Wàn jiàn chuānxīn bì dìng bǎidú bù qīn' means 'When ten thousand arrows pierce the heart, one must become immune to all poisons.' It represents emotional toughness built up after going through extreme pain.