Agniveshyagrihyasutra 3.6.2

At this time his kinsmen, with dishevelled hair—those who are present—shave their hair and beard.

For others, it is optional:

they may shave or they may refrain.

However, by one who has Vedic learning, [the hair] must certainly be shaved even if he is absent; such is the opinion in the ritual text of Baudhāyana.

Those who have returned home after graduation should not shave except in the sacrificial enclosure, say some.

Upon [the death of] a mother, father, or teacher, there is food free from alkaline and salt, sleeping on the ground, and chastity for three nights; for three days, six days, twelve days, a year, as long as it takes to acquire [learning], or up to twelve days; in the case of foremost elders, there is water libation for the dead thus; in the case of others, for three nights; for as long as she lives in the case of the deceased's wife.

Now, if one who has set up the sacred fires should die elsewhere, they should dwell while [the fires] are kept burning and invoked until they bring his body together with the fires.

Then, having milked this milk of a cow whose calf is of another mother, having caused it to overflow on the Gārhapatya, he should cause it to overflow on the Āhavanīya.

"They bring the kindling stick from below, for from above they bring [it] to the gods"—thus it is known [from scripture].

Then, having taken him up and carried him out towards the north between the sacrificial altar and the rubbish heap, they should burn him in the established manner.

Now, if one who has set up the sacred fires should die elsewhere, having drawn three firehouses at the water's edge, having entered once, having closed the eyes, and having restrained [the breath], he should look towards the sun, [facing] south with bowed shoulders.

And he should prepare [it].

In this very manner, three times for one who is in a foreign land.

Now, if he should be burned, having brought the bones, having made the shape of a man out of the bones on a black antelope skin inside the altar, having piled the sacrificial vessels on top of them, and having covered them with young kuśa shoots, they should burn him in the established manner.

Now, if one cannot find the bones, having made the shape of a man out of three hundred and sixty leaf-stalks of palāśa on a black antelope skin, having piled the sacrificial vessels on top of them, and having covered them with young kuśa shoots, they should burn him in the established manner.

"They burn one who has set up the sacred fires with his fires and with the sacrificial vessels"—thus it is known [from scripture].

"For an offering of a man is dearest to him"—this they declare as the explanation for the burning.

Moreover they cite: "The fires indeed become heirs of the body."

That also is known in the Ṛgveda: "A hundred autumns indeed are before us, O gods, during which you have appointed old age for our bodies,

where sons become fathers; do not harm our life halfway to its end."