Patanjali Yoga Sutra — Pariṇāmatāpa saṃskāraduḥkhairguṇavṛttivirodhācca duḥkhameva sarvaṃ vivekinaḥ॥2.15॥

परिणामताप-संस्कारदुःखैर्गुणवृत्तिविरोधाच्च दुःखमेव सर्वं विवेकिनः ॥

Every experience is destined to lead to pain ultimately, due to consequences (pariṇāma), inherent afflictions (tāpa) and impressions (saṃskāra) it might lead to. Hence, an enlightened sādhaka treats all experiences as agonizing.

Leave alone the painful experiences even the seemingly pleasurable experiences have three perils ingrained. They are: Pariṇāma (its temporary nature and consequential attachment it might lead to at the end), tāpa (inherent sorrow it has) and saṃskāra (impressions it might give rise to). This mundane pleasure is embedded in three qualities (guṇas) and obviously, never a sādhaka is free from their influences. Even a worldly pleasurable experience has an inbuilt fear of losing. Hence, an enlightened sādhaka rejects all sensory or worldly experiences as painful alone.

Besides recommending triguṇātīta bhāva (Transcendence of all three guṇas) for sādhakas, Bhagavān opines that true happiness cannot be anything less than being one with Supreme Soul.

विषयेन्द्रियसंयोगाद्यत्तदग्रेऽमृतोपमम्।

परिणामे विषमिव तत्सुखं राजसं स्मृतम्॥गीता १८.३८॥

Viṣayendriyasaṃyogādyattadagre’mṛtopamam|

Pariṇāme viṣamiva tatsukhaṃ rājasaṃ smṛtam॥Gītā 18.38॥

The experience born out of union (saṃyoga) of sense organs (indriyas) and their objects (viṣaya), though appears to be ambrosia (amṛta) and pleasurable at first sight, is not so, as it transforms into poison (viṣam) at the end (pariṇāma). Such an experience is called Rajas.