Bhagavad Gita Chapter 8.24
agnir jyotir ahaḥ śuklaḥ
ṣaṇ-māsā uttarāyaṇam
tatra prayātā gacchanti
brahma brahma-vido janāḥ
Translation
Those who know the Supreme Brahman attain that Supreme by passing away from the world during the influence of the fiery god, in the light, at an auspicious moment of the day, during the fortnight of the waxing moon, or during the six months when the sun travels in the north.