Gobhilagrihyasutra 1.7

He then washes the mortar, the pestle, and the winnowing basket, strews to the west of the fire eastward-pointed Darbha grass, and puts (the mortar, &c.) on (that grass).

He then pours out, with a brazen vessel or with the pot in which the oblations of cooked rice are prepared, the grain destined for sacrifice, rice or barley—

Once pronouncing the name of the deity (to whom the offering will be made): 'Agreeable to such and such (a deity) I pour thee out;' twice (it is done) silently.

Then to the west, with his face turned eastward, he begins to husk the grain, with his right hand lying over the left.

After the grain has three times been winnowed, he should wash it thrice (if it is destined) for the gods, they say, twice, if for men, once, if for the Fathers.

Having put a (Darbha) purifier (into the pot in which the oblation is to be prepared), he should pour the grain (into it).

He should cook the mess of sacrificial food so that it is well cooked, stirring it up (with the pot-ladle) from left to right.

When it has been cooked, he should sprinkle (Âgya) on it, should take it from the fire towards the north, and should again sprinkle (Âgya) on it.

Having put wood on the fire, he should strew Kusa grass round it on all sides, to the east, to the south, to the north, to the west—

On all sides in three layers or in five layers—

Thick, so that always an uneven number (of blades) are put together.

(He should strew) eastward-pointed grass, covering the roots with the points.

Or he should strew it to the west (of the fire), and should draw (some of the grass which he has strewn) from the south end and (some) from the north end, in an easterly direction.

He should (arrange the grass so as to) lay the points of the southern blades uppermost.

This rule for strewing (grass) round (the fire is valid) for all (ceremonies) at which oblations are made.

Some lay also branches of Samî wood or of Parna wood round (the fire).

To the north (of the fire) a Sruva full of water (is placed): this is the Pranîta water;

If there is (such water). Or it may be dispensed with, say some (teachers).

Having put the mess of cooked food on the Barhis, and put wood (on the fire), he prepares the Âgya.

(He may take) ghee, or oil made from Tila seeds, or curds, or milk, or rice gruel.

From that same Barhis (he takes two Darbha blades and) makes purifiers (of them), of the length of one span.

Putting an herb between (them and the instrument with which he cuts them), he cuts them off, not with his nail, with (the words), 'Purifiers are ye, sacred to Vishnu.'

He then wipes them with water, with (the words), 'By Vishnu's mind ye are purified.'

Having purified (the Âgya by pouring it into the Âgya pot, over which he has laid a Darbha purifier), he purifies it (in the pot) with the two northward-pointed purifiers (in the following way):

Holding them with his two thumbs and fourth fingers, he purifies (the Âgya) three times, from west to east, once with the Yagus: 'May the god Savitri purify thee with this uninjured purifier, with the rays of the good sun;' twice silently.

He then should sprinkle them with water and should throw them into the fire.

Then, having put that Âgya on the fire, he should take it from (the fire) towards the north.

This is the way to prepare the Âgya.