Shiva Purana
सद्भिराचरितत्वाच्च सदाचारः स उच्यते ॥ सदाचारस्य तस्याहुरास्तिक्यं मूलकारणम् ॥ ५८ ॥
Good conduct is also the conduct of the good. Theism is the source of goodness.
english translation
sadbhirAcaritatvAcca sadAcAraH sa ucyate ॥ sadAcArasya tasyAhurAstikyaM mUlakAraNam ॥ 58 ॥
hk transliteration by Sanscript