Shatapatha Brahmana 2.5.1.13

2.5.1.13

sa aikṣata prajāpatiḥ | parā me pūrvāḥ prajā abhūvannimā u cedime vimathnate na tataḥ kiṃ cana pariśekṣyata iti tebhya etam bhāgamakalpayadetam mārutaṃ saptakapālam puroḍāśaṃ sa eṣa mārutaḥ saptakapālastadyatsaptakapālo bhavati sapta sapta hi māruto gaṇastasmānmārutaḥ saptakapālaḥ puroḍāśo bhavati

Pragâpati reflected, 'My former creatures have passed away; and if those (Maruts) destroy these (creatures), then nothing will be left.' He accordingly set aside for them that share, the Maruts' cake on seven potsherds; and that is this same cake on seven potsherds for the Maruts. The reason why it is one of seven potsherds, is that the host of the Maruts is (distributed in troops) of seven each. This is why there is a cake on seven potsherds for the Maruts.