Agniveshyagrihyasutra 2.5.8

Now, the spit-ox sacrifice. Year after year, it should be performed on the full moon of Mārgaśīrṣa,

or under Ārdrā. Having built the fire in the forest, having strewn all around, having performed [the rites] up to the carrying of the Praṇītā water, having taken the barhis grass, he dedicates the cow with: "I dedicate you, agreeable to Īśāna."

"Silently," say some.

Right there, he immolates her with her head turned to the west and feet turned to the north.

For her, once immolated, there is aspersion with water.

Having replenished the vital breaths, having pulled out the omentum silently, he takes out the heart,

and the customary cut-off portions.

Having pierced them on these very spits, they cook them in this very fire.

Then, having removed them from the spits, they boil them down again in a cooking pot.

Then, having removed them after basting with clarified butter, he bastes [them] when set down.

Having performed [the rites] from the laying of the enclosing sticks up to the face of the fire, he invokes the deity: "May the tawny horses bring you, mindful, along with white horses having banners;

swift as the wind, bountiful, fleet as thought, come quickly to my oblation, O Śarva! Om."

Then, with the sruva dipping-spoon, he offers [the omentum] that has been under-poured and basted [with clarified butter].

Having recited the invitatory verse, "Thousands by thousands...", he offers with the offering verse, "Thee, Īśāna, the glory of the worlds...".

Then he offers subsidiary clarified butter oblations.

Here, having sliced these cut-off portions upon the offering platter, having mixed together the boiled rice, meat, and broth with clarified butter, he offers them by scooping with the wooden ladle in the eastern half [of the fire], saying:

"Svāhā to the god Bhava! Svāhā to the god Śarva! Svāhā to the god Īśāna! Svāhā to the god Paśupati! Svāhā to the god Rudra! Svāhā to the god Ugra! Svāhā to the god Bhīma! Svāhā to the god Mahān!"

Then in the middle [he offers]: "Svāhā to the wife of the god Bhava! Svāhā to the wife of the god Śarva! Svāhā to the wife of the god Īśāna! Svāhā to the wife of the god Paśupati! Svāhā to the wife of the god Rudra! Svāhā to the wife of the god Ugra! Svāhā to the wife of the god Bhīma! Svāhā to the wife of the god Mahān!"

Then he offers in the western half:

"Svāhā to the son of the god Bhava! Svāhā to the son of the god Śarva! Svāhā to the son of the god Īśāna! Svāhā to the son of the god Paśupati! Svāhā to the son of the god Rudra! Svāhā to the son of the god Ugra! Svāhā to the son of the god Bhīma! Svāhā to the son of the god Mahān!"

Then he offers clarified butter oblations,

with "Homage to your wrath, O Rudra..." up to the end of the section.

From the Sviṣṭakṛt oblation onward, [the ritual] is established up to the giving of a choice cow [as dakṣiṇā].

Then, behind the fire, he places the remnant of the oblation upon arka leaves with: "Rudra who is in the fire, who is in the waters, who is in the plants, Rudra who has entered all worlds—to that Rudra be homage!"

Having collected the washings of the cooking pot, the remainder of the clarified butter, and the remainder of the water into a vessel, and having sprinkled [the cattle] with a reed branch, he goes clockwise three times around the cows with this hymn: "The cows have come and brought good fortune...".

They call it a great rite for well-being.

Now, if he does not obtain a cow, he seizes a ram or a goat.

Or he cooks a pot of boiled rice for Īśāna, performing what is to be done with a cow.

That spit-ox sacrifice has been explained.

In this very way it should be performed on the eighth lunar day in the evening; this alone is different:

there is no dedicating of an animal here. ||8