Atharvavedaparishishta 3.1.13

3.1.13

tasmāt kulīnaṃ śrotriyaṃ bhṛgvaṅgirovidaṃ vinayākṛtiśaucācārayuktam alolupaṃ vrataniyamacāritravṛttalakṣanaguṇasaṃpannaṃ saṃdhivigrahacintakaṃ māhendrajālaprabhṛtikarmādiṣv abhividakaṃ jitasthānāsanaṃ himātapavarṣasahaṃ hrīdhṛtikam ārjavaṃ śamadamadayādānaśaktisaṃpannaṃ bṛhaspatyuśanasoḥ sthānākṛtipramāṇaṃ varṇāśrutavapuṣā cānumeyaṃ tejasvinaṃ gambhīraṃ sattvayuktaṃ guruṃ vṛṇīyād bhūpatir iti ||

Therefore, the king should choose as his guru one who is of noble birth, learned in the Veda, knowing the Bhṛgus and Aṅgirases, endowed with discipline, handsome appearance, purity, and good conduct, free from greed, endowed with the qualities of vows, restraints, moral conduct, virtuous practice, and auspicious marks, thoughtful of peace and war, proficient in rites such as great sorcery, having conquered his standing and sitting postures, enduring cold, heat, and rain, having shame and firmness, upright, endowed with calmness, self-control, compassion, and generosity, having the position, appearance, and standard of Bṛhaspati and Uśanas, inferable by color, sacred learning, and body, radiant, profound, and possessed of sattva.