Bhagavad Gita 10.20
अहमात्मा गुडाकेश सर्वभूताशयस्थितः। अहमादिश्च मध्यं च भूतानामन्त एव च।।10.20।।
ahamātmā guḍākeśa sarvabhūtāśayasthitaḥ| ahamādiśca madhyaṃ ca bhūtānāmanta eva ca||10.20||
ahamatma gudakesha sarvabhutashayasthitah ahamadishca madhyam ca bhutanamanta eva ca10.20
Meaning
Krishna is the Self seated in the hearts of all beings, the beginning, the middle, and the end of all beings. He is both the innermost essence and the cosmic totality.
हे गुडाकेश! मैं समस्त प्राणियों के हृदय में स्थित आत्मा हूँ; सम्पूर्ण सृष्टि का आदि, मध्य, और अन्त भी मैं ही हूँ।
This is verse 20 of 42 in Chapter 10 (Vibhooti Yoga) of the Bhagavad Gita.