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.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
चतुर्युगसहस्रं च ब्रह्मणो दिनमुच्यते । स कल्पो यत्र मनवश्चतुर्दश विशाम्पते
caturyugasahasraṃ ca brahmaṇo dinamucyate | sa kalpo yatra manavaścaturdaśa viśāmpate
SB 12.4.2