Śatapatha Brāhmaṇa ("of a hundred paths") 6.3.3.10

6.3.3.10

yadvevākramayati | etadvai devā abibhayuryadvai na imamiha rakṣāṃ si nāṣṭrā na hanyuriti tasmā etaṃ vajramupariṣṭadabhigoptāramakurvannamumevādityamasau vā āditya eṣo 'śvastathaivāsmā ayametaṃ vajramupariṣṭādabhigoptāraṃ karoti

And, again, why he makes it step thereon;--the gods then were afraid, thinking, 'We hope the Rakshas, the fiends, will not slay here this our (Agni)!' They placed that thunderbolt upon him as a protector, to wit, yonder sun; for that horse is indeed yonder sun; and in like manner does this (Sacrificer, or priest) now place upon him that thunderbolt as a protector.