Bhavishyapurana 3.4.9

Bhaviṣyapurāṇa 3.4.9

vyatyastapāṇinā kāryamupasaṅgrahaṇaṃ guroḥ .
savyena savyaḥ spraṣṭavyo dakṣiṇena tu dakṣiṇaḥ . . 9