Bhagavatapurana 5.9.5

5.9.5

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sa cāpi tad u ha pitṛ-sannidhāv evāsadhrīcīnam iva sma karoti chandāṃsy adhyāpayiṣyan saha vyāhṛtibhiḥ sapraṇava-śiras tripadīṃ sāvitrīṃ graiṣma-vāsantikān māsān adhīyānam apy asamaveta-rūpaṃ grāhayām āsa //

5. But in the presence of his father the son (Bharata) made the teaching appear as thrown away on him; for the father intending to teach him the Vedas taught him first the Vyahritis and Gayatri (the three-footed) with the sacred syllable. Though he studied for four months from Chaitra (spring and summer), the father was able to make him learn only a few disconnected syllables.