戶樞不蠹

Simplified: 户枢不蠹

hùshūbùdù ㄏㄨˋ ㄕㄨ ㄅㄨˋ ㄉㄨˋ

    • lit. a door hinge never becomes worm-eaten
    • constant activity prevents decay (idiom)

Character by character

Sources