Śatapatha Brāhmaṇa ("of a hundred paths") 6.2.1.37

6.2.1.37

taddhaike | ityevaitāni paśuṣīrṣāṇi vittvopadadhatyubhayenaite paśava iti te ha te martyāḥ kuṇapāḥ sambhavantyanāprītāni hi tāni taddha tathāṣāḍheḥ sauśromateyasyopadadhuḥ sa ha kṣipra eva tato mamāra

Now some, having in that way obtained those heads, put them on (the fire-altar), thinking, 'Either way are they animals.' But they (who do this) become mortal carcases, for unpropitiated are those (heads) of theirs. In this way, indeed, they did put them on for Ashâdhi Sausromateya; but quickly indeed he died after that.