Bhagavad Gita Chapter 8 Verse 17
भगवद् गीता अध्याय 8 श्लोक 17

सहस्रयुगपर्यन्तमहर्यद्ब्रह्मणो विदुः।
रात्रिं युगसहस्रान्तां तेऽहोरात्रविदो जनाः।।8.17।।



हिंदी अनुवाद - स्वामी रामसुख दास जी ( भगवद् गीता 8.17)
।।8.17।।जो मनुष्य ब्रह्माके सहस्र चतुर्युगीपर्यन्त एक दिनको और सहस्र चतुर्युगीपर्यन्त एक रातको जानते हैं वे मनुष्य ब्रह्माके दिन और रातको जाननेवाले हैं।


English Translation of Sanskrit Commentary By Sri Shankaracharya's
8.17 Viduh, they know; that ahah, day; brahmanah, of Brahma, of Prajapati, of Virat; yat, which; sahasra-yuga-paryantam, ends in a thousand yugas; and also the ratirm, night; yuga-sahasra-antam, which ends in a thousand yugas, having the same duration as the day. Who knows (these)? In reply the Lord says: Te, they; janah, poeple; ahoratra-vidah, who are the knowers of what day and night are, i.e. the people who know the measurement of time. Since the worlds are thus delimited by time, therefore they are subject to return.
What happens during the day and the night of Prajapati is being stated:


English Translation of Commentary  - Dr. S. Sankaranarayan
8.17 See Comment under 8.19


English Translation of Ramanuja's Sanskrit Commentary
8.17 These men who know the order of the day and night as established by My will in regard to all beings, beginning with man and ending with Brahma - they understand that what forms Brahmas day is a unit comprising in it a thousand periods of four Yugas (Catur-yugas) and anight is a unit of eal duration.


Transliteration Bhagavad Gita 8.17Sahasrayugaparyantam aharyad brahmano viduh;
Raatrim yugasahasraantaam te’horaatravido janaah.


Word Meanings Bhagavad Gita 8.17sahasra—one thousand; yuga—age; paryantam—until; ahaḥ—one day; yat—which; brahmaṇaḥ—of Brahma; viduḥ—know; rātrim—night; yuga-sahasra-antām—lasts one thousand yugas; te—they; ahaḥ-rātra-vidaḥ—those who know his day and night; janāḥ—people