因小失大

yīnxiǎoshīdà
to save a little only to lose a lot (idiom)

CEDICT

to try to save a little only to lose a lot; to spoil the ship for a ha'p'orth of tar; to be penny wise and pound foolish

Wiktionary

為了小緣故而貽誤大事。《兒女英雄傳．第二三回》：「再說看那姑娘的見識心胸，大概也未必肯吃這注，倘然因小失大，轉為不妙。」也作「為小失大」。

重編國語辭典

Entry Composition

=1 因 yīn old variant of 因 yīn
=1 因 yīn
  1. cause
  2. reason
  3. because
2 小 xiǎo
  1. small
  2. tiny
  3. few
  4. young
3 失 shī
  1. to lose
  2. to miss
  3. to fail
4 大 dà
  1. big; large; great
  2. older (than another person)
  3. eldest (as in 大姐 dàjiě)
  4. greatly; freely; fully
  5. (dialect) father
  6. (dialect) uncle (father's brother)