Bhagavatapurana 7.14.39

7.14.39

dṛṣṭvā teṣāṃ mitho nṛṇāmavajñānātmatāṃ nṛpa /
tretādiṣu harerarcā kriyāyai kavibhiḥ kṛtā //

39. O king, in Treta and other later ages, seeing that men were disposed to look upon one another with contempt and disregard, wise men instituted Hari's image for the purpose of worship and other duties towards Him.