兄弟阋于墙，外御其侮

兄弟鬩於墻，外禦其侮
xiōngdìxìyúqiáng,wàiyùqíwǔ
internal disunity dissolves at the threat of an invasion from outside (idiom)

CEDICT

Entry Composition

1 兄弟 xiōngdì
  1. brothers
  2. younger brother
  3. I, me (humble term used by men in public speech)
  4. brotherly
  5. fraternal

classifier: 個
2 阋 xì
  1. to argue
  2. to quarrel
=3 于 yú
  1. to go
  2. to take
  3. sentence-final interrogative particle
  4. variant of 于 yú
=3 于 yú
  1. (of time or place) in; at; on
  2. (indicating any indirect relation) to; toward; vis-à-vis; with regard to; for
  3. (indicating a source) from; out of
  4. (used in comparison) than
  5. (used in the passive voice) by
=4 墙 qiáng variant of 墙 qiáng
=4 墙 qiáng (slang) to block (a website) (usu. in the passive: 被墙 bèiqiáng)

classifiers: 面, 堵
5 外 wài
  1. outside
  2. in addition
  3. foreign
  4. external
=6 御 yù
  1. (bound form) imperial; royal
  2. (literary) to drive (a carriage)
  3. (literary) to manage; to govern
=6 御 yù (bound form) to defend; to resist
7 其 qí
  1. his
  2. her
  3. its
  4. their
  5. that
  6. such
  7. it (refers to sth preceding it)
8 侮 wǔ
  1. to insult
  2. to ridicule
  3. to disgrace