Shatapatha Brahmana 5.2.5.10

5.2.5.10

sa yadagnīṣomīyaḥ | ekādaśakapālaḥ puroḍāśo bhavatyagnirvai dātā varcaḥ somastadasmā agnireva dātā varco dadāti

Now as to why there is that cake on eleven potsherds for Agni and Soma;--Agni is the giver, and Soma is glory: thus Agni, the giver, gives him glory.