小洞不補大洞吃苦 [－－－补－－－－]

Jyutping siu2 dung6 bat1 bou2 daai6 dung6 hek3 fu2
Pinyin xiǎo dòng bù bǔ dà dòng chī kǔ

Definitions (CC-CEDICT)
  1. A small hole not plugged will make you suffer a big hole (idiom); a stitch in time saves nine