北叟失馬 [－－－马]

Jyutping bak1 sau2 sat1 maa5
Pinyin běi sǒu shī mǎ

Definitions (CC-CEDICT)
  1. lit. the old man lost his horse, but it all turned out for the best (idiom)
  2. fig. a blessing in disguise
  3. it's an ill wind that blows nobody any good