Bhagavad Gita · 8.3

श्रीभगवानुवाचअक्षरं ब्रह्म परमं स्वभावोऽध्यात्ममुच्यते।भूतभावोद्भवकरो विसर्गः कर्मसंज्ञितः॥

śhrī bhagavān uvācha akṣharaṁ brahma paramaṁ svabhāvo 'dhyātmam uchyate bhūta-bhāvodbhava-karo visargaḥ karma-sañjñitaḥ

The Supreme Lord said: The imperishable is called Brahman, the supreme reality. One's own nature is called the Self. The creative force that brings about the existence of beings is called karma.

— Bhagavad Gita 8.3

Source: Sacred-Texts.com (Sanskrit) + Bhagavad-Gita.io (translations)