Jaiminīya (Talavakāra) Brāhmaṇa 2-8.287

The four-day rite indeed accords with day and night. With the first day he spreads out the day; with the second, the banner of the day. With the third day he spreads out the night; with the fourth, that which is the banner of the day in the morning. Day and night indeed bring forth all this. [He thinks:] 'May those two who bring forth all this bring forth [offspring] for me!' And he should also say: 'The four-day rite accords with the directions.' Four are the directions; the upward direction is the fifth. These days are four; the night is the fifth. Through this he prospers in the directions. Established in the directions, he goes to the heavenly world. Of this [rite] there are these upasad-offerings accompanied by sacrificial cakes. The sacrificial cake is the womb, the clarified butter is the seed. In that he offers clarified butter after offering the sacrificial cake, they establish the seed right in the womb. Properly the seed poured by him is born, who knows thus. And in whatever deities he offers the sacrificial offerings, in them he prospers. Established in them, he goes to the heavenly world.

Now comes this [four-day rite] belonging to Prajāpati.

One who desires procreation should sacrifice with this.

Prajāpati desired: 'May I become manifold, propagated with offspring and cattle!'