Jaiminīya (Talavakāra) Brāhmaṇa 20.91

Now the Yaṇvasantani sāman: from the fifth day the gods fashioned the sixth day. The fifth day is as if with a gap. When they praise at the beginning of the midday purifying laud with the Yaṇvasantani, it is for the continuity of the day, for the gaplessness of the day. He who knows this stands firm. Prajāpati created cattle; created, they went away from him. He desired: "May I hold the cattle in myself." He saw this sāman; with it he held the cattle in himself. In that he held (ayacchat) the cattle in himself, that is the yaṇva-nature of the Yaṇva. The Udgātṛ is this Prajāpati; he holds the cattle in himself by means of the Yaṇva. The fifth day is the central turning day of the twelve-day rite. The Yaṇvasantani is at the beginning, the Santani at the end. By means of the Yaṇvasantani they continue the earlier three-day period, and by the Santani the subsequent one.

Indra could not endure the limits.

He desired: "May I endure the limits."

He saw this sāman.

With it he sang praise.

Then indeed he endured the limits.

In that this sāman is [used], it is for the enduring of the limits.

For it he chants the prastāva three times; he responds once; they join in the finale three times.