Śatapatha Brāhmaṇa ("of a hundred paths") 4.4.3.5

4.4.3.5

taṃ vā apurorukkaṃ gṛhṇāti | candobhyo hyenaṃ gṛhṇāti sa yadevainaṃ candobhyo gṛhṇāti teno hāsyaiṣa puroruṅnānbhavati tasmādapurorukkaṃ gṛhṇāti

He draws it without a puroruk-formula, for he draws it for the metres; and in that he draws it for the metres, even thereby that (graha) of his becomes supplied with a puroruk: therefore he draws it without a puroruk.