Śatapatha Brāhmaṇa ("of a hundred paths") 14.2.2.6

14.2.2.6

indrāya tvā vasumate rudravate svāheti ayam vā indro yo'yam pavate tasmā evainaṃ juhoti tasmādāhendrāya tveti vasumate rudravata iti tadindramevānu vasūṃśca rudrāṃścābhajatyatho prātaḥsavanasya caivaitanmādhyandinasya ca savanasya rūpaṃ kriyate

[Vâg. S. XXXVIII, 8,] 'To Indra, accompanied by the Vasus and Rudras, (I offer) thee, hail!'--Indra indeed is he who blows here: it is to him he thus offers it, and therefore he says, 'To Indra--thee;' and when he says, 'accompanied by the Vasus and Rudras,' thereby he allows a share to the Vasus and Rudras along with Indra; and, moreover, it is thereby made to be like the morning Soma-pressing, and the midday-pressing.