Śatapatha Brāhmaṇa ("of a hundred paths") 2.5.4.8

2.5.4.8

athaindrāgnau dvādaśakapālaḥ puroḍāśo bhavati | etena haivainamaghnaṃstejo vā agnirindriyaṃ vīryamindra etābhyāmenamubhābhyāṃ vīryābhyāmaghnanbrahma vā agniḥ kṣatramindraste ubhe saṃrabhya brahma ca kṣatraṃ ca sayujau kṛtvā tābhyāmenamubhābhyāṃ vīryābhyāmaghnaṃstasmādaindrāgno dvādaśakapālaḥ puroḍāśo bhavati

Then follows a cake on twelve, potsherds for Indra and Agni; for by means of that they slew him, since Agni means fiery glow (tegas), and Indra means manly power, and by means of these two powers they did indeed slay him. Moreover, Agni is the priesthood, and Indra is the nobility; having allied these two, having closely united the priesthood with the nobility, they (the gods) slew him by means of these two powers: hence there is a cake on twelve potsherds for Indra and Agni.