Bhagavad Gita · 11.47

श्रीभगवानुवाचमया प्रसन्नेन तवार्जुनेदंरूपं परं दर्शितमात्मयोगात्।तेजोमयं विश्वमनन्तमाद्यंयन्मे त्वदन्येन न दृष्टपूर्वम्॥

śhrī bhagavān uvācha mayā prasannena tavārjunedaṁ rūpaṁ paraṁ darśhitam ātma-yogāt tejo-mayaṁ viśhvam anantam ādyaṁ yan me tvad-anyena na dṛṣhṭa-pūrvam

The Supreme Lord said: Being pleased with you, O Arjuna, I have shown you by my own yogic power this supreme, radiant, universal, infinite, primeval form — which no one before you has ever seen.

— Bhagavad Gita 11.47

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)