Mahabharata 12.280.5

वर्णोत्कर्षमवाप्नोति नरः पुण्येन कर्मणादुर्लभं तमलब्धा हि हन्यात्पापेन कर्मणा

varṇotkarṣamavāpnoti naraḥ puṇyena karmaṇādurlabhaṃ tamalabdhā hi hanyātpāpena karmaṇā

Our plain-language meaning of this verse is waiting for scholar review.