An extent of a thousand ages (yugas), which they know as the day of Brahma, And a night ending in a thousand ages, those men are the knowers of day and night.
When they know that a day of Brahma stretches over a thousand eons, and his night ends in a thousand eons, men understand day and night.
(17) For a thousand ages lasts [one] day of Brahma, and for a thousand ages [one such] night: this knowing, men will know [what is meant by] day and night.
8.17 Those people who are knowers of what day and night are, know the day of Brahma which ends in a thousand yugas [The four yugas (in the human worlds), viz Satya, Treta, Dwapara, and Kali are made up of 4,320,000 years. This period multiplied by a thousand constitutes one day of Brahma. His night also extends over an equal period. See M.S. and V.S.A.], and His night which ends in a thousand yugas.
8.17
8.17 Those people who know the day of Brahma which is of a duration of a thousand Yugas (ages) and the night which is also of a thousand Yugas duration, they know day and night.