深藏若虛 [－－－虚]

Jyutping sam1 cong4 joek6 heoi1
Pinyin shēn cáng ruò xū

Definitions (CC-CEDICT)
  1. to hide one's treasure away so that no-one knows about it (idiom); fig. modest about one's talents
  2. to hide one's light under a bushel