Garudapurana 2.6.24

2.6.24

aṣṭamūrteradhiṣṭhānamataḥ śāntiṃ prayaccha me /
gaṅgāyamunayoḥ peyamantarvedi tṛṇaṃ cara //

you are the abode of the Eight-formed [Śiva]; therefore grant peace to me! / Drink of the Gaṅgā and Yamunā, and graze on the grass in the intermediate altar-land!