Hiranyakeshigrihyasutra 2.1.3.9

2.1.3.9

athāto medhājananam \ darbheṇa hiraṇyaṃ prabadhya tadantardhāyopariṣṭātprāñcaṃ kumāraṃ dhāryamāṇaṃ ghṛtaṃ prāśayati \ bhūrṛcastvayi juhomi svāhā \ bhuvo yajūṃṣi tvayi juhomi svāhā \ suvaḥ sāmāni tvayi juhomi svāhā \ bhūrbhuvaḥ suvaratharvāṅgirasastvayi juhomi svāhā \ iti \9\

Now (follows) the medhâganana (or production of intelligence). With (an instrument of) gold over which he has laid a Darbha shoot tied (to that piece of gold) he gives to the child, which is held so that it faces the east, ghee to eat, with the formulas, 'Bhûh! I sacrifice the Rikas over thee! Bhuvah! I sacrifice the Yagus over thee! Suvah! I sacrifice the Sâmans over thee! Bhûr bhuvah suvah! I sacrifice the Atharvan and Aṅgiras hymns over thee!'