Bhagavad Gita Chapter 13, Verse 30

यदा भूतपृथग्भावमेकस्थमनुपश्यति | तत एव च विस्तारं ब्रह्म सम्पद्यते तदा ||

yadā bhūta-pṛthag-bhāvam eka-stham anupaśyati tata eva ca vistāraṁ brahma sampadyate tadā

When one sees the separate existence of all beings as situated in one and sees their expansion from that, then one attains Brahman.

Krishna describes the vision that leads to Brahman. 'Yadā bhūta-pṛthag-bhāvam eka-stham anupaśyati'—when one sees the separate existence of all beings as situated in one. When you see all separate beings as having their source in one Supreme, you see unity. 'Tata eva ca vistāram'—and sees their expansion from that. When you see all beings as expanding from the one Supreme, you see the relationship. 'Brahma sampadyate tadā'—then one attains Brahman. When you have this vision—seeing all separate beings as coming from one source, seeing their expansion from that source—you attain Brahman. You realize the unity behind diversity. You see the one source of all. This is the realization of Brahman—the ultimate reality, the source of all.