Skandapurana 16.17.153

16.17.153

iṃdraṃ mitraṃ tṛtīyā tu ṛkcaiva parikīrtitā ..
kṛṣṇaṃ niyānaṃ hi tathā caturthī parikīrtitā .. 153 ..

and ‘Indraṃ mitraṃ’ is celebrated as the third ṛg-verse; / ‘Kṛṣṇaṃ niyānam’ indeed is celebrated as the fourth;