Bhagavatapurana 12.8.9

12.8.9

kṛṣṇājinaṃ sākṣa-sūtraṃ kuśāṃś ca niyamarddhaye /
agny-arka-guru-viprātmasv arcayan sandhyayor harim //

9. For the enhancement of righteousness, he wore deer-skin, a string of beads and sacred grass, and both in the morning and evening, devoutly worshipped Hari present in Agni, Surya, his preceptor, the wise brahmins and in his own self.