兄弟

xiōng dì brothers; younger brother; CL:個|个[ge4]; I, me (humble term used by men in public speech); brotherly; fraternal

阋

xì to argue; to quarrel

于

yú to go; to take; sentence-final interrogative particle; variant of 於|于[yu2]

Yú surname Yu

Yú surname Yu

yú in; at; to; from; by; than; out of

墙

qiáng variant of 牆|墙[qiang2], wall

qiáng wall; CL:面[mian4],堵[du3]

， 外御其侮

wài yù qí wǔ internal disunity dissolves at the threat of an invasion from outside (idiom)