Jñāneśvarī (commentary on the Bhagavadgītā) 4.80

4.80

etha ekaci he dhanuṣyapāṇī |
parī jāhale gā cahūṃ varṇīṃ |
aisī guṇakarmī kaḍasaṇī |
kelī sahajeṃ ||

Here [humanity] is but one, O wielder of the bow, / yet it has become four varṇas; / thus the separation was naturally made / through guṇas and actions.