Śrī Karabhājana replied: In each of the four yugas, or ages — Kṛta, Tretā, Dvāpara and Kali — Lord Keśava appears with various complexions, names and forms and is thus worshiped by various processes.
Srimad Bhagavata Purana
श्रीमद्भागवतमहापुराणम्
मूल श्लोकः
करभाजन उवाच । कृतं त्रेता द्वापरं च कलिरित्येषु केशवः । नानावर्णाभिधाकारो नानैव विधिनेज्यते
karabhājana uvāca | kṛtaṃ tretā dvāparaṃ ca kalirityeṣu keśavaḥ | nānāvarṇābhidhākāro nānaiva vidhinejyate
SB 11.5.20