Chapter 13 · The Field and the Knower · Krishna said
Bhagavad Gita 13.21 — Who acts, who experiences
कार्यकारणकर्तृत्वे हेतुः प्रकृतिरुच्यते। पुरुषः सुखदुःखानां भोक्तृत्वे हेतुरुच्यते ॥
kāryakāraṇakartṛtve hetuḥ prakṛtirucyate | puruṣaḥ sukhaduḥkhānāṃ bhoktṛtve heturucyate ||
Meaning
Nature is said to be the cause of the body, the senses and all action. The Self is said to be the cause of experiencing pleasure and pain.