兄弟阋于墙

借指内部不和。鲁迅《二心集·上海文艺之一瞥》： “有些貌似革命的作品，也并非要将本阶级或资产阶级推翻，倒在憎恨或失望于他们不能改良，不能较长久的保持地位，所以从无产阶级的见地看来，不过是 ‘兄弟阋于墙’ ，两方一样是敌对。”
○ 兄弟阋墙

兄弟阋于墙

成语。《诗经·小雅·常棣》：“兄弟阋于墙，外御其侮。”“阋”意为争斗。原意是，自己家的兄弟有矛盾，尽可以在家相争，但如果有别人来欺侮自己家的人，就应团结起来，一致对外。这是儒家“亲亲疏疏”原则的具体表现。后来人用“兄弟阋于墙”表示内部争斗。

兄弟阋于墙兄弟阋墙xiōng dì xì yú qiáng

brothers at loggerheads; brothers fight at home;brothers squabble inside the walls; internal dispute;quarrel (/dissension) between brothers
❍ 所以从无产阶级的见地看来，不过是“～”，两方一样是敌对。(鲁迅《二心集·上海文艺一瞥》93) From the working-class point of view,this is simply “brothers at loggerheads”fighting inside the enemy’s camp. 一阶级里，临末也常常会把自己互相闹起来的，就是诗经里说的那“～”，——但后来却未必 “外御其侮”。(《鲁迅选集》Ⅲ—75)Members of one class often end by quarrelling among themselves,as witness the Book of Songs: “Brothers fight at home.” But it does not necessarily follow that“They resist an attack from outside.”/～，外御其务。(《诗经·小雅·常棣》) Brothers indoors may fight;|But insults from without|Join them at once,and they unite|The common foe to rout.
❍ ～，外御其侮。(《左传·僖二十五年》) Brothers may squabble inside the walls. |But they will resist insult from without.
❍ 尝闻兄弟阋墙，每为孔方作崇；戈操同室，常因财产纠纷。(赵树理《三里湾》 113) Whereas it has come to our ears that dissension between brothers arises perpetually over lucre,and inasmuch as strife within a household springs frequently from disputes over the estate. …

兄弟阋于墙xiōnɡ dì xì yú qiánɡ

阋：争吵。比喻内部相争。quarrel between brothers, internal dispute, brothers fighting at home

兄弟阋于墙xiōngdìxìyúqiáng

〔主谓〕 阋，争吵。墙，这里指家内，泛指内部。原指兄弟龃龉不和睦，发生纠纷。后比喻内部纷争。语出《诗经·小雅·常棣》：“兄弟阋于墙，外御其务（侮）。”鲁迅《二心集·上海文艺之一瞥》：“所以从无产阶级的见地看来，不过是‘～ ’，两方一样是敌对。”
△ 贬义。多指兄弟争吵。
【近义】兄肥弟瘦 同室操戈
〖反义〗同仇敌忾。
也作“兄弟阋墙”。