nirañjanaṁ nirguṇam advayaṁ paraṁ
tvāṁ jñāpti-mātraṁ puruṣaṁ vrajāmy aham
The word nirguṇam here indicates that the Lord’s existence is beyond the qualities of material nature. One might argue that Lord Kṛṣṇa’s body is made of material nature, but here the word advayam refutes that argument. There is no duality in Lord Kṛṣṇa’s existence. His eternal, spiritual body is Kṛṣṇa, and Kṛṣṇa is God.