AITAREYA UPANISHAD · 2.1.4

सोऽस्यायमात्मा पुण्येभ्यः कर्मभ्यः प्रतिधीयते । अथास्यायमितर आत्मा कृतकृत्यो वयोगतः प्रैति । स इतः प्रयन्नेव पुनर्जायते तदस्य तृतीयं जन्म ॥ ४ ॥

so’syāyamātmā puṇyebhyaḥ karmabhyaḥ pratidhīyate । athāsyāyamitara ātmā kṛtakṛtyo vayogataḥ praiti । sa itaḥ prayanneva punarjāyate tadasya tṛtīyaṃ janma ॥ 4 ॥

Lo this is the spirit and self of him and he maketh it his vicegerent for the works of righteousness. Now this his other self when it hath done the works it came to do and hath reached its age, lo! it goeth hence, and even as it departeth, it is born again. And this is the third birth of the Spirit.

Sri Aurobindo · CWSA 18, p. 203