अहमात्मा गुडाकेश सर्वभूताशयस्थितः ।अहमादिश्च मध्यं च भूतानामन्त एव च ॥
In plain words
I am the Self residing within the hearts of all beings, Arjuna. I am their beginning, their middle, and their end.
Close to the Sanskrit
I am the Self, O Guḍākeśa, seated in the hearts of all beings; I am the beginning and the middle and the end of beings indeed and.