Bhagwad Gita
Chapter 8, Verse 24
अग्निर्ज्योतिरहः शुक्लः षण्मासा उत्तरायणम्।
तत्र प्रयाता गच्छन्ति ब्रह्म ब्रह्मविदो जनाः।।8.24।।
Those who know the Supreme Brahman pass away from the world during the influence of the fiery god, in the light, at an auspicious moment, during the fortnight of the moon and the six months when the sun travels in the north.