Srimad-Bhagavatam: Canto 10 - Chapter 1 - Verse 45


अहं हि सर्वभूतानामादिरन्तोऽन्तरं बहि: ।भौतिकानां यथा खं वार्भूर्वायुर्ज्योतिरङ्गना: ॥ ४५ ॥


ahaṁ hi sarva-bhūtānāmādir anto ’ntaraṁ bahiḥbhautikānāṁ yathā khaṁ vārbhūr vāyur jyotir aṅganāḥ


Dear ladies, I am the beginning and end of all created beings and exist both within and without them, just as the elements ether, water, earth, air and fire are the beginning and end of all material objects and exist both within and without them.


According to Śrīla Śrīdhara Svāmī and Śrīla Viśvanātha Cakravartī, Lord Kṛṣṇa implies the following idea in this verse: “If you know that I am the Supreme Lord, there should be no question of your suffering any separation from Me, since I pervade all existence. Your unhappiness must be due to a lack of discrimination. Therefore please take this instruction from Me, which will remove your ignorance. “But the truth of the matter is that you gopīs were in your previous lives great masters of yoga, and thus you must already know this science of jñāna-yoga. Furthermore, whether I try to teach this to you in person or through My representative, such as Uddhava, it will not produce the desired result. Jñāna-yoga simply causes suffering for those who are fully immersed in pure love of Godhead.”