Bhagavad Gita 10.15 Chapter 10, Verse 15

स्वयमेवात्मनाऽत्मानं वेत्थ त्वं पुरुषोत्तम ।
भूतभावन भूतेश देवदेव जगत्पते ॥१०.१५॥

svayamevātmanā'tmānaṃ vettha tvaṃ puruṣottama
bhūtabhāvana bhūteśa devadeva jagatpate

Meaning

You alone know yourself by yourself, O Supreme Person — source of beings, Lord of beings, God of gods, Lord of the universe.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 10.15 (Chapter 10, The Yoga of Divine Glories (Vibhuti Yoga), Verse 15)