Shatapatha Brahmana 5.4.4.23

5.4.4.23

athākṣānnivapati | svāhākṛtāḥ sūryasya raśmibhiryatadhvaṃ sajātānām madhyameṣṭhyāyetyeṣa vā agniḥ pṛthuryadadhidevanaṃ tasyaite 'ṅgārā yadakṣāstamevaitena prīṇāti tasya ha vā eṣānumatā gṛheṣu hanyate yo vā rājasūyena yajate yo vaitadevaṃ vedaiteṣvakṣeṣvāha gāṃ dīvyadhvamiti pūrvāgnivāhau dakṣiṇā

He (the Adhvaryu) throws down the dice, with, 'Hallowed by Svâhâ, strive ye with Sûrya's rays for the middlemost place among brethren!' For that gaming-ground is the same as 'ample Agni,' and those dice are his coals, thus it is him (Agni) he thereby pleases; and assuredly in the house of him who offers the Râgasûya, or who so knows this, the striking of that cow is approved of. On those dice he says, 'Play for the cow!' The two draught oxen of the original (hall-door) fire are the sacrificial fee.