平生不做亏心事，半夜敲门心不惊
píng​shēng​bù​zuò​kuī​xīn​shì, bàn​yè​qiāo​mén​xīn​bù​jīng

clear conscience

平生不做亏心事，半夜敲门心不惊 (平生不做虧心事，半夜敲門心不驚) píng​shēng​bù​zuò​kuī​xīn​shì, bàn​yè​qiāo​mén​xīn​bù​jīng
clear conscience
Having never done anything wrong or shameful, one does not need to fear unexpected visitors or sudden troubles.

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Definitions
CC-CEDICT