Mudgalapurana 3.16.10

3.16.10

brāhmaḥ kṛtayuge dharmaścatuṣpādaḥ sanātanaḥ |
tretāyāṃ tripadaḥ prokto dharmo dharmavidāṃ varaiḥ ||

Dharma relating to Brahman in the Kṛta age has four feet and is eternal; / in Tretā, dharma is declared to have three feet by the best among knowers of dharma;