Jaiminīya Upaniṣad Brāhmaṇa 2.13.5

2.13.5

tad yad iha puruṣasya pāpaṃ kṛtam bhavati tad āviṣkaroti
yad ihainad api rahasīva kurvan manyate 'tha hainad āvir eva karoti
tasmād vāva pāpaṃ na kuryāt /
pañcame 'nuvāke prathamaḥ khaṇḍaḥ //

Whatever evil is done here by a man, that it brings to light. Even what one thinks he does here in secret, as it were, that it brings to light. Therefore, one should not do evil. / First khaṇḍa in the fifth anuvāka.