Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 66
Sanskrit:
याज्ञवल्क्यस्ततो ब्रह्मंश्छन्दांस्यधिगवेषयन् ।गुरोरविद्यमानानि सूपतस्थेऽर्कमीश्वरम् ॥ ६६ ॥
ITRANS:
yājñavalkyas tato brahmaṁśchandāṁsy adhi gaveṣayanguror avidyamānānisūpatasthe ’rkam īśvaram
Translation:
My dear brāhmaṇa Śaunaka, Yājñavalkya then desired to find out new yajur-mantras unknown to even his spiritual master. With this in mind he offered attentive worship to the powerful lord of the sun.