(idiom) internecine strife; brothers fighting at home, used to describe internal disputes or fighting among oneself. From a line in the [[诗经|詩經|shi1 jing1]] that says "brothers quarrel inside the walls, but join together to resist outside insults."

(literary) to quarrel within the family; refers to siblings falling out or a group suffering from internal conflict or infighting

internal disunity dissolves at the threat of an invasion from outside; siblings may fight at home but will join forces against outsiders

to knit one's brows; to frown

(literary) internal trouble; disaster caused by domestic strife or infighting between brothers