Bhagavad Gita 8.25 Chapter 8, Verse 25

धूमो रात्रिस्तथा कृष्णः षण्मासा दक्षिणायनम् ।
तत्र चान्द्रमसं ज्योतिर्योगी प्राप्य निवर्तते ॥८.२५॥

dhūmo rātristathā kṛṣṇaḥ ṣaṇmāsā dakṣiṇāyanam
tatra cāndramasaṃ jyotiryogī prāpya nivartate

Meaning

Smoke, night, the dark fortnight and the six months of the sun's southern course — by this path the yogi reaches the lunar light and returns.

Newly written by Bhajan Dhun — scholarly review in progress.

Reference: Bhagavad Gita 8.25 (Chapter 8, The Yoga of the Imperishable Absolute, Verse 25)