Srimad-Bhagavatam: Canto 12 - Chapter 1 - Verse 2
Sanskrit:
चतुर्युगसहस्रं तु ब्रह्मणो दिनमुच्यते ।स कल्पो यत्र मनवश्चतुर्दश विशाम्पते ॥ २ ॥
ITRANS:
catur-yuga-sahasraṁ tubrahmaṇo dinam ucyatesa kalpo yatra manavaścaturdaśa viśām-pate
Translation:
One thousand cycles of four ages constitute a single day of Brahmā, known as a kalpa. In that period, O King, fourteen Manus come and go.