Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 33
Sanskrit:
तयोर्द्विजवरस्तुष्ट: शुद्धभावानुवृत्तिभि: ।प्रोवाच वेदानखिलान्सङ्गोपनिषदो गुरु: ॥ ३३ ॥
ITRANS:
tayor dvija-varas tuṣṭaḥśuddha-bhāvānuvṛttibhiḥprovāca vedān akhilānsāṅgopaniṣado guruḥ
Translation:
That best of brāhmaṇas, the spiritual master Sāndīpani, was satisfied with Their submissive behavior, and thus he taught Them the entire Vedas, together with their six corollaries and the Upaniṣads.