家丑不可外传 (家醜不可外傳) jiāchǒu bù kě wàizhuàn

jiāchǒu bù kě wàizhuàn phrase family shames must not be aired in public
Domain: Proverb 谚语
Notes: (CC-CEDICT '家醜不可外傳')

Also contained in

家丑不可外传,流言切莫轻信