Apastambagrihyasutra 1.1: prathamaḥ khaṇḍaḥ

Now (follow) the ceremonies (the knowledge of) which is derived from practice (and not from the Sruti).

They should be performed during the northern course of the sun, on days of the first fortnight (of the month), on auspicious days,

With the sacrificial cord suspended over (the sacrificer's) left shoulder.

(The rites should be performed) from left to right.

The beginning should be made on the east side or on the north side,

And also the end.

Ceremonies belonging to the Fathers (are performed) in the second fortnight (of the month),

With the sacrificial cord suspended over the right shoulder,

From right to left,

Ending in the south.

Ceremonies occasioned by special occurrences (are performed) according as their occasions demand.

Having set the fire in a blaze, he strews eastward-pointed Darbha grass around it,

Or eastward-pointed and northward-pointed (grass);

Southward-pointed at sacrifices to the Fathers,

Or southward-pointed and eastward-pointed.

To the north of the fire he strews Darbha grass and (on that) he places the vessels (required for sacrifice) upside-down, two by two, if referring to ceremonies directed to the gods,

All at once, if to men,

One by one, if to the Fathers.

The preparation of the (blades used as) 'purifiers,' the measure of their length, the preparation of the Prokshanî water, and the sprinkling of the vessels are the same here as at the sacrifices of the new and full moon, (but are performed) in silence.

To the west of the fire he pours water into a vessel over which he has laid (two grass blades called) purifiers, purifies (the water) three times with two northward-pointed purifiers, holds it on a level with his nose and mouth, places it to the north of the fire on Darbha grass, and covers it with Darbha grass.

On the south side he causes a Brâhmana to sit down on Darbha grass.

He melts the Âgya, pours it, to the west of the fire, into the Âgya-pot, over which he has laid two purifiers, draws coals (out of the sacrificial fire) towards the mirth, puts (the Âgya) on them, throws light on it by means of a burning (grass-blade), throws two Darbha points into it, moves a firebrand round it three times, takes it from the fire towards the north, sweeps the coals back (into the fire), purifies (the Âgya) three times with two northward-pointed purifiers, moving them backward and forward, and throws the purifiers into the fire.