Skandapurana 3.3.19.162

3.3.19.162

ṛgvedamaṣṭame varṣe navame yajuṣāṃ gaṇam .
daśame sāmavedaṃ ca līlayādhyagamatsudhīḥ .. 78 ..

The wise boy mastered with ease the Ṛgveda in his eighth year, the collection of Yajus verses in the ninth,
and the Sāmaveda in the tenth year.