Kauṣītaki Upaniṣad 3.8.14-17

3.8.14

sukhaduḥkhayor vijñātāraṃ vidyāt /

Pleasure and pain are not what one should desire to understand. One should know the discerner of pleasure and pain.

3.8.15

nānandaṃ na ratiṃ na prajātiṃ vijijñāsīta /

Bliss, delight, and procreation are not what one should desire to understand. One should know the discerner of bliss, delight, and procreation.

3.8.16

ānandasya rateḥ prajāter vijñātāraṃ vidyāt /

3.8.17

netyāṃ vijijñāsīta /

Going is not what one should desire to understand. One should know the goer.