Puruṣottama Yoga · Verse 16

द्वाविमौ पुरुषौ लोके क्षरश्चाक्षर एव च | क्षरः सर्वाणि भूतानि कूटस्थोऽक्षर उच्यते

dvāv imau puruṣau loke kṣaraś cākṣara eva ca | kṣaraḥ sarvāṇi bhūtāni kūṭa-stho 'kṣara ucyate

Two are these Puruṣas in the world: the perishable and the imperishable. The perishable are all beings; the imperishable is called the immutable.

Dual classification of the Puruṣa. Two (dvau) puruṣa in the loke (world): kṣara (perishable, mutable) and akṣara (imperishable, immutable).

The kṣaraḥ is sarva bhūtāni — all individual conditioned beings, which constantly change. The akṣara is kūṭa-stha — the one at the peak, immutable, stable as a mountain. This duality corresponds to the individual jiva (kṣara) and the universal jīvātman or to the primordial nature in potential state (prakṛti).