Śatapatha Brāhmaṇa ("of a hundred paths") 6.7.4

He then stands by him worshipping with the Vâtsapra rite, For Pragâpati, having by means of the Vishnu-strides produced creatures, created vital power for them by means of the Vâtsapra rite; and in like manner the Sacrificer, having, by means of the Vishnu-strides, produced creatures (or, subjects), creates vital power for them by means of the Vâtsapra rite.

Now the Vâtsapra rite, doubtless, is he, the golden-handed (Agni);--hence whomsoever that is born one may wish to obtain the full (measure of) life, let him touch that one with the Vâtsapra rite, and he thereby creates vital power for that newborn one; and accordingly that one obtains the full (measure of) life. And whomsoever one may wish to be vigorous, let him first address that one with the Vikriti (fashioning) formula, and that one accordingly becomes vigorous.

[Vâg. S. XII, 18-20] 'From the sky Agni was first born;'--the sky, doubtless, is the breath, and from the breath he (Agni) was indeed first born,--'from us the second time, the knower of beings,'--inasmuch as he, man-like, on that occasion generated him a second time;--'the third time in the waters,'--inasmuch as he there did generate him a third time from the waters;--'he, the manly-minded, (kindling him) the imperishable,'--the manly-minded, doubtless, is Pragâpati; and the imperishable, Agni;--'kindling him the mindful praises (gar) him,'--for he who kindles him generates him, mindful.

'We know, O Agni, thy threefold three,'--Agni, Vâyu (wind), Âditya (sun), these are his three in three forms;--'We know thy manifold scattered sites,'--inasmuch as he (Agni) is here distributed many ways;--'we know thy highest name which is in secret,'--'the youngest,' that indeed is his highest name in secret;--'we know that source whence thou art come;'--the source, doubtless, is the (heavenly) waters, for from the waters he first came.

'In the sea the manly-minded (kindled) thee, in the waters,'--the manly-minded is Pragâpati: thus, 'In the waters Pragâpati (kindled) thee;'--'the man-watcher hath kindled thee, O Agni, in the udder of the sky,'--the man-watcher, doubtless, is Pragâpati, and the udder of the sky is the waters;--'thee, whilst standing in the third region,'--the third region, doubtless, is the sky;--'the buffaloes made (thee) grow in the lap of the waters;'--the buffaloes, doubtless, are the vital airs: thus, 'the vital airs made thee grow in the sky.'

These (three verses) have one and the same explanation regarding him (Agni): they are Trishtubh verses relating to Agni. Inasmuch as they relate to Agni, they are Agni; and inasmuch as they are Trishtubhs, and eleven (syllables), they are Indra;--but Agni consists of Indra and Agni: as great as Agni is, as great as is his measure, with so much he thus stands worshipping by him. And Indra and Agni are all the gods, and Agni includes (or belongs to) all the deities: as great as Agni is, as great as is his measure, with so much he thus stands worshipping by him.

And, again, why the Vishnu-strides and the Vâtsapra rite are (performed);--by the Vishnu-strides Pragâpati created this world, and by the Vâtsapra the fire (Agni); by the Vishnu-strides Pragâpati created the air, and by the Vâtsapra the wind (Vâyu); by the Vishnu-strides Pragâpati created the sky, and by the Vâtsapra the sun (Âditya); by the Vishnu-strides Pragâpati created the regions, and by the Vâtsapra the moon; by the Vishnu-strides Pragâpati created that which has been, and by the Vâtsapra that which shall be; by the Vishnu-strides Pragâpati created possession (wealth), and by the Vâtsapra hope; by the Vishnu-strides Pragâpati created the day, and by the Vâtsapra the night; by the Vishnu-strides Pragâpati created the former (bright) fortnights, and by the Vâtsapra the latter (dark) fortnights; by the Vishnu-strides Pragâpati created the half-months, and by the Vâtsapra the months; by the Vishnu-strides Pragâpati created the seasons, and by the Vâtsapra the year: thus the reason why the Vishnu-strides and Vâtsapra are (performed) is that he thereby even now creates everything.

And, again, why the Vishnu-strides and the Vâtsapra rite are (performed). By the Vishnu-strides Pragâpati drove up to heaven. He saw that unyoking-place, the Vâtsapra, and unyoked thereat to prevent chafing; for when the yoked (beast) is not unloosed, it is chafed. In like manner the Sacrificer drives up to heaven by the Vishnu-strides; and unyokes by means of the Vâtsapra.

Having stridden the Vishnu-strides, he then forthwith stands by the fire worshipping it with the Vâtsapra, just as one who has journeyed would forthwith unyoke. Men (proceed) after the manner of the gods: hence even now, when a troop of men have journeyed they forthwith unyoke.

Now, the Vishnu-strides indeed are the day and the night, and the Vâtsapra is the day and the night: he thus journeys for a day and a night, and takes rest for a day and a night: and hence even now when a troop of men have journeyed for a day and a night they take rest for a day and a night.

Only for one half of the year he strides the Vishnu-strides, and for one half he worships the fire with the Vâtsapra; for the world of heaven is in the midst of the year: thus were he to stride for less than half (a year), he would not reach that world of heaven; and were he to do so for more than half (a year), he would pass beyond that world of heaven and lose it; but when he strides for one half, and worships the fire for one half, he unyokes forthwith after reaching the world of heaven.

He proceeds with these two alternately, even as one would accomplish a long way by (repeatedly) unyoking. Both before and after (the Dîkshâ), he combines both, the Vishnu-strides and the Vâtsapra; for the Vishnu-strides are the day, and the Vâtsapra the night; and Pragâpati, both when he was about to generate and when he had generated this universe, enclosed it on both sides by day and night: in like manner the Sacrificer now, both when he is about to generate and when he has generated this universe, encloses it on both sides by day and night.

As to this they say, 'If the Vishnu-strides are the day, and the Vâtsapra the night, and both of them are (performed) during the day, not during the night, how then are they both performed for (or by) him also during the night?' Well, on that (first) occasion, when he is being initiated, he, at the outset, combines both (performances) in the afternoon; for the afternoon is the same thing as the night. Then throwing them thus together, he at the end combines them both in the forenoon; for the forenoon is the same thing as the day; and in this way they are both performed during the day, and both during the night.

Now early on the day on which he may intend to combine them, when the sun has risen, he first throws out the ashes (from the pan); having thrown out the ashes, he releases his speech; having released his speech, he puts on a kindling-stick; having put on a kindling-stick, he takes the ashes down to (and throws them into) the water. In the same way as he takes them down he returns after taking some of the ashes; and having thrown it into the pan he stands reverentially by the fire. He then performs two expiations.