Muṇḍaka Upaniṣad · 3.2.12

अशरीरं शरीरेष्वनवस्थेष्ववस्थितम् । महान्तं विभुमात्मानं मत्वा धीरो न शोचति

aśarīraṃ śarīreṣv anavastheṣv avasthitam | mahāntaṃ vibhum ātmānaṃ matvā dhīro na śocati

Incorporeal, among bodies that are not his is established; knowing the great, the all-pervading Self, the serene does not grieve.

The Self is not the body, and knowing it frees from suffering.

Aśarīram — incorporeal, formless. The Ātman is not bodily or spatially limited.

Śarīreṣu anavastheṣu — among bodies that are not his. Bodies are instruments, temporary possessions, not identity.

Avasthitam — established, present. Not as owner but as witness, as consciousness.

Mahāntam vibhum — the great, the all-pervading. Without limits, present in everything.

Ātmānam matvā — knowing the Self. Not intellectually but directly realizing.

Dhīraḥ na śocati — the serene does not grieve. Suffering arises from identification with the limited; knowing the unlimited, pain ceases.

Śoka — lamentation, grief, suffering. There is no possible loss for one who knows that the Self never dies.

This is the fruit of yoga: equanimity in the face of all vicissitudes.