Shatapatha Brahmana 10.1.4.10

10.1.4.10

taddhaitacāṇḍilyaśca sāptarathavāhaniśca ācāryāntevāsibau vyūdāte rūpamevāsyaitaditi ha smāha śāṇḍilyo lomānīti sāptarathavāhaniḥ

Now, on this point, Sândilya and Sâptarathavâhani, teacher and pupil, were once disputing with one another: 'This is his form,' said Sândilya; 'his hair,' said Sâptarathavâhani.