Verse 17

Those people who know 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 a similar period. See M.S. and V.S.A.], and His night which also ends in a thousand yugas.