失之毫厘，謬以千里 [－－－－－谬－－－]

Jyutping sat1 zi1 hou4 lei4 , mau6 ji5 cin1 lei5
Pinyin shī zhī háo lí , miù yǐ qiān lǐ

Definitions (CC-CEDICT)
  1. a tiny lapse can lead to a huge mistake (idiom); a minor discrepancy leading to enormous losses