Śatapatha Brāhmaṇa ("of a hundred paths") 3.5.4.21

3.5.4.21

so 'vastṛṇāti | rakṣohaṇo vo valagahano 'vastṛṇāmi vaiṣṇavānityatha barhīṃṣi tanūnīvopariṣṭātpracādayati keśā haivāsyaite

He spreads it with, 'You, the Rakshas-killers, the charm-killers, Vishnu's own, I spread.' He, as it were, covers the bodies on the top, for that (grass) is indeed his (Vishnu's) hair.