Mahabharata 12.12.4

12.12.4

anāstikānāstikānāṃ prāṇadāḥ pitaraśca ye |
te'pi karmaiva kurvanti vidhiṃ paśyasva pārthiva |
vedavādāpaviddhāṃstu tānviddhi bhṛśanāstikān || 4 ||

"Nakula said, 'The very gods had established their fires in the region called Visakha-yupa. Know, therefore, O king, that the gods themselves depend upon the fruits of action. The Pitris, that support (by rain) the lives of even all disbelievers, observing the ordinances (of the Creator as declared in the Vedas), are, O king, engaged in action. Know them for downright atheists that reject the declaration of the Vedas (which inculcate action). The person that is learned in the Vedas, by following their declarations in all his acts, attains, O Bharata, to the highest region of heaven by the way of the deities.