ㄐㄧㄡˇㄅㄧㄥˋjiǔbìngㄔㄥˊchéngㄌㄧㄤˊliángyī

久病成良医
  1. 經常生病熟知醫藥知識比喻經過長久歷練自然成為內行

long illness makes the patient into a good doctor (idiom)​