Hiranyakeshigrihyasutra 1.2.7

He then causes (the student) to put on the fire seven pieces of fresh Palâsa wood, with unbroken tops, of one span's length, which have been anointed with ghee.

One (of these pieces of wood he puts on the fire) with (the Mantra), 'To Agni I have brought a piece of wood, to the great Gâtavedas. As thou art inflamed, Agni, through that piece of wood, thus inflame me through wisdom, insight, offspring, cattle, holy lustre, and through the enjoyment of food. Svâhâ!'—

(Then he puts on the fire) two (pieces of wood with the same Mantra, using the dual instead of the singular), 'To Agni (I have brought) two pieces of wood;'

(Then) four (pieces of wood, using the plural), 'To Agni (I have brought) pieces of wood.'

He then sprinkles (water) round (the fire) as above.

'Thou hast given thy consent;' 'Thou hast given thy impulse'—thus he changes the end of each Mantra.

He then worships the (following) deities (with the following Mantras),

Agni with (the words), 'Agni, lord of the vow, I shall keep the vow;'

Vâyu with (the words), 'Vâyu, lord of the vow, (&c.);'

Âditya (the sun) with (the words), 'Âditya, lord of the vow, (&c.);'

The lord of the vows with (the words), 'Lord of the vows, ruling over the vows (&c.).'

He then gives an optional gift to his Guru (i.e. to the teacher).

(The teacher) makes him rise with (the verse which the student recites), 'Up! with life' (Taitt. Samh. I, 2, 8, 1); he gives him in charge (to the sun) with (the words), 'Sun! This is thy son; I give him in charge to thee;' and he worships the sun with (the Mantra), 'That bright eye created by the gods which rises in the east: may we see it a hundred autumns; may we live a hundred autumns; may we rejoice a hundred autumns; may we be glad a hundred autumns; may we prosper a hundred autumns; may we hear a hundred autumns; may we speak a hundred autumns; may we live undecaying a hundred autumns; and may we long see the sun.'

'May Agni further give thee life. May Agni further grant thee bliss. May Indra with the Maruts here give (that) to thee; may the sun with the Vasus give (it) to thee'—with (this verse the teacher) gives him a staff, and then hands over to him a bowl (for collecting alms).

Then he says to him, 'Go out for alms.'

Let him beg of his mother first;

Then (let him beg) in other houses where they are kindly disposed towards him.

He brings (the food which he has received) to his Guru (i.e. to the teacher), and announces it to him by saying, '(These are) the alms.'

(The teacher accepts it) with the words, 'Good alms they are.'

'May all gods bless thee whose first garment we accept. May after thee, the prosperous one, the well-born, many brothers and friends be born'—with (this verse the teacher) takes (for himself) the former garment (of the student).

When the food (with which the Brâhmanas shall be entertained) is ready, (the student) takes some portion of boiled rice, cakes, and flour, mixes (these substances) with clarified butter, and sacrifices with (the formulas), 'To Agni svâhâ! To Soma svâhâ! To Agni, the eater of food, svâhâ! To Agni, the lord of food, svâhâ! To Pragâpati svâhâ! To the Visve devâs svâhâ! To all deities svâhâ! To Agni Svishtakrit svâhâ!'

Thus (let him sacrifice) wherever (oblations of food are prescribed) for which the deities (to whom they shall be offered) are not indicated.