Śatapatha Brāhmaṇa ("of a hundred paths") 7.4.2.21

7.4.2.21

yāste agne sūrye ruco | yā vo devāḥ sūrye ruca iti rucaṃ rucamityamṛtatvaṃ vai rugamṛtatvamevāsminnetaddadhāti dvābhyāmupadadhāti tasyokto bandhuratho dvayaṃ hyevaitadrūpam mṛccāpaśca sādayitvā sūdadohasādhivadati tasyokto bandhuḥ

[He lays down the dviyagus brick, with Vâg. S. XIII, 22, 23] 'O Agni, what lights of thine in the sun overspread the sky by their beams, with all those help us to light and to people!--O ye gods, what lights of yours are in the sun, and what lights are in kine and horses, O Indra and Agni, with all those bestow light upon us, O Brihaspati!' for 'light' he prays each time: light being immortality, it is immortality he thus bestows on him (Agni, and the Sacrificer). With two (verses) he lays it down: the significance of this has been explained. And, moreover, it is because that material form (of the brick) is a twofold one, (consisting as it does of) clay and water. Having 'settled' it, he pronounces the Sûdadohas upon it: the significance of this has been explained.