At the outset of yajña (yajna) ceremonies, the priest of Ṛgveda (Rigveda), or ṛtvika (ritwika) used to execute the functions of both the priest and the hotā (hota) or the performer of the yajña.

[See Ṛtvika, Hotā]

Later, when the rituals of a yajña became more intricate, four priests or ṛtvika of Caturveda (Chaturveda) were appointed separate vedic tasks. It was the duty of a priest known as adhvaryu to pray to and invoke by chants, the worshipped gods. The simultaneous reference to both the hotā and adhvaryu in the same chants in Ṛgveda signifies that perhaps it was since the time of Ṛgveda itself that the procedures of performing a yajña became more complex, leading to the division of tasks among priests. In one place in Ṛgveda there is mention of the Ṛgvedic (Rigvedic) hotā addressing the adhvaryu, “O adhvaryu! Both of us together shall sing hymns of praise, answer me—

śaṃsāvadhāryo prati me gṛṇīhīndrāya vāhaḥ kṛṇavāva juṣṭam.

It can be understood from this chant that during a yajña ceremony, the tradition of the adhvaryu uttering a statement as an indication to the hotā to deliver the chants to invoke the gods, and the hotā replying by beginning the recitation of chants, started during the era of Ṛgveda as well.

• Usually, the primary ṛtvika or priest of Yajurveda was known as adhvaryu. It was only after a priest became adept in the rituals and procedures of Yajurveda that he became an adhvaryu—

ādhvaryavaṃ yajurbhistu ṛgibharhotraṃ tathaiva ca.

All major tasks related to the yajña were performed by the adhvaryu, and no work could be undertaken without his instructions. Yāska (Yaska) in his Nirukta, has defined the word adhvaryu. One who connects the adhvara or yajña to everything, from the recitation of the chants to singing sāmagāna (samagana, or the hymns and songs in Vedas), along with other rituals, is known as adhvaryu—adhvaraṃ yunakti iti adhvaryuḥ.

In Śatapatha Brāmaṇa (Satapatha Brahmana), the adhvaryu has been referred to as ‘pūrvādha‘ (purvadha) or the most important part of a yajña, and accorded with the most respected stature among all. It is only after the adhvaryu instructs him that the priest of Ṛgveda, while invoking the gods, recites the anuvākyā (anuvakya) and yājyāmantra (yajyamantra) chants.  Apart from offering the main oblations at the yajña the adhvaryu performs Yajurvedic rituals in Daśapūrṇamāsayāga (Dashapurnamashayaga, yāga meaning yajña) which is performed by one along with one’s wife. In Somayāga (Somayaga), the adhvaryu offers an oblation of somarasa in a container known as ‘graha‘; in Rājasūyayāga, he performs the coronation ceremony of the king. It is said in Śatapatha Brāhmaṇa, that the adhvaryu, during the Agnicayana (Agnichayana) ceremony, besides undertaking all other necessary responsibilities, also used to sing hymns (sāmagāna).

• In view of the tasks carried out by the adhvaryu, we can assume that Yājñavalkyakya (Yajnavalkya) himself performed Yudhiṣṭhira’s (Yudhisthira’s) coronation ceremony, because Yājñavalkya was the adhvaryu at the Rājasūya yajña organised by Yudhiṣṭhira. The great sage Piṅgala (Pingala), who was appointed as the adhvaryu at King Janamejaya’s Sarpasatra yajña, performed the rituals of the ceremonies there. The Ātmavān (Atmavan) sage Jamadagni was the adhvaryu at Hariśacandra’s (Harishachandra’s) Puruṣamedha (Purushamesha) yajña. At Candra’s (Chandra’s) Rājasūya yajña, Bhṛgu (Bhrigu) performed the rites of his coronation ceremony.

• It is said in Matsyapurāṇa (Matsyapurana) that parama puruṣa (parama purusha or the Supreme Man) created the adhvaryu from his own arm.

• Apparently, there was only a single Yajurveda from where the chants to be recited by the adhvaryu, the ādhvarya (adhvarya) chants were conceived. According to Vāyupurāṇa (Vayupurana), God Vyasa, the one who divided Vedas, marked 12000 hymns as ādhvarya chants to be learned by the adhvaryu.

[See Ṛtvik]

• It is believed that adhvaryu, hotā and wood required for the yajña fire have originated from the front, back, right and left limbs respectively of the sacrificial boar which has been conceptualised as the presiding deity of yajña.