Jaiminīya (Talavakāra) Brāhmaṇa 37.215

Now the Pauruhanmana: it is an overlapping, a sliding back of the sacrifice. It overlaps the ninth day; it runs back to the seventh. By overlappings, indeed, the gods excluded the Asuras from the sacrifice. Puruhanman Vaikhānasa, desiring cattle, performed asceticism. He saw this sāman. He praised with it. He came to this iḷā. Cattle, indeed, are the iḷā. Thence indeed he obtained cattle. This is a sāman that brings cattle. He obtains cattle, he becomes rich in cattle, who knows thus. And because Puruhanman Vaikhānasa saw it, it is called Pauruhanmana. The gods and the Asuras were contending. Those gods desired: 'May we strike down the Asuras first!' They saw this sāman. They praised with it. By it, they struck down the Asuras first. In that they struck them down first, that is the nature of the Pauruhanmana. He strikes down his hateful rival first, who knows thus.

Now the Dvaigata having the word-finale, [which belongs to] the Rathantara.

Therefore it is performed on the Rathantara-day.

The gods, having gathered up the entire sacrifice, departed upward to the heavenly world.

Those humans did not know the sacrifice.