Mahabharata 5.104.21

दक्षिणां कां प्रयच्छामि भवते गुरुकर्मणिदक्षिणाभिरुपेतं हि कर्म सिध्यति मानवम्

dakṣiṇāṃ kāṃ prayacchāmi bhavate gurukarmaṇidakṣiṇābhirupetaṃ hi karma sidhyati mānavam

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