Agniveshyagrihyasutra 2.3.1

Now, having swept up three times with a wood splinter on a pure, level ground in the fire-sanctuary, having cast away the splinter, having touched water, and having sprinkled the fire with water, he throws [it] up.

"Whatever impurity of it there is, that he strikes away; he sprinkles with water for pacification," says a Brāhmaṇa [passage].

Having sifted pure, white, non-moist sand to the amount of five prasthas, having made a sacrificial ground, square, measuring an aratni, sloping toward the northeast, measuring a span, he draws a line to the east on the south with grains of rice; likewise in the middle; likewise on the north.

With grains of rice he draws a line to the north on the west; likewise in the middle; likewise on the east.

Having pushed aside the rice grains, having touched water, having sprinkled with water, having established the fire with "Bhūr bhuvaḥ svaḥ om, be established!", the sacred grass measuring an aratni, thirty-six aṅgulas [long], three wooden pins as enclosing sticks, with the middle finger, the ring finger, and the little finger: the thickest in the middle, the thinner on the south, the thinnest and shortest on the north; the fuel stick twelve thumbs [long], sacrificial wood of eighteen [thumbs], the sprinkling-water pot, the ghee pot, the vessel for Prajāpati measuring a quarter-prastha, a full two-quarter-prastha vessel for carrying forward the praṇītā water, a prastha-pot for the cooked offering, the size of a portion stated as a thumb-joint, the measure of an oblation four aṅgulas, the size of the ladle twenty-one thumbs, its forward part fourteen thumbs, its raised [rim] two thumbs, its cavity five thumbs; likewise the offering-spoon measuring a span, the strainer likewise, the poker likewise—thus the specification of measurements for the offering has been explained. || 1