रज:सत्त्वसमायुक्तो मानुषेषु प्रपद्यते रजस्तमोभ्यां संयुक्तस्तिर्यग्योनिषु जायते,रजोगुण और सत्त्वगुणसे संयुक्ति होनेपर वह मनुष्य-लोकमें जाता है तथा रजोगुण और तमोगुणसे संयुक्त होनेपर वह पशु-पक्षी आदिकी योनियोंमें जन्म ग्रहण करता है
rajaḥ-sattva-samāyukto mānuṣeṣu prapadyate | rajas-tamobhyāṃ saṃyuktas tiryag-yoniṣu jāyate ||
Yājñavalkya explains that the soul’s next embodiment follows the predominance of the guṇas: when rajas is conjoined with sattva, one is born among human beings; but when rajas is conjoined with tamas, one is born into the wombs of animals and birds.
याज़्वल्क्य उवाच
Rebirth is conditioned by the dominant guṇic mixture: rajas with sattva leads to human birth, while rajas with tamas leads to birth among animals/birds. Ethical cultivation of sattva is implied as it supports a higher, more dharmically capable embodiment.
In a didactic discourse within Śānti Parva, the sage Yājñavalkya instructs his listener(s) on how the guṇas determine the destination of the jīva after death, mapping moral-psychological qualities to corresponding realms of birth.