Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 23
Sanskrit:
यदावतीर्णो भगवान् कल्किर्धर्मपतिर्हरि: ।कृतं भविष्यति तदा प्रजासूतिश्च सात्त्विकी ॥ २३ ॥
ITRANS:
yadāvatīrṇo bhagavānkalkir dharma-patir hariḥkṛtaṁ bhaviṣyati tadāprajā-sūtiś ca sāttvikī
Translation:
When the Supreme Lord has appeared on earth as Kalki, the maintainer of religion, Satya-yuga will begin, and human society will bring forth progeny in the mode of goodness.