垣堅くして犬入らず（かきかたくしていぬいらず）

Japanese vocabulary

Meaning: a wholesome household can not be disturbed from the outside; a house divided against itself cannot stand; a firm fence keeps the dogs out

See it used in real works

• Example sentences from Japanese novels & web fiction (Massif)
• Hear “垣堅くして犬入らず” pronounced in real videos (YouGlish)