The Pancharatra is a group of texts as old as the four Vedas and has the same transcendental origin. They were ancient even in the time of the Lord Krishna’s appearance in this world, and are mentioned in the Shanti-parva section of the Mahabharata.
In that portion a description of the transcendental abode Swetadwipa is given, ‘a domain inhabited by devotees of Narayana, whom they worship through their knowledge of pancha-ratra.’ The name pancha-ratra means ‘Five Nights,’ and indicates a series of instructions given by Lord Narayana to His devotees over five consecutive nights. Narada Muni heard them first and shared them with Lord Shiva, Lakshmi Devi, the Kumaras and others. There are said to be around two hundred texts including the Ahirbudhnya Samhita spoken by Shiva, the Lakshmi Tantra, and the Narada Pancharatra. Srila Prabhupada writes:
The scriptures known as the Pañcarātra-śāstras are recognized Vedic scriptures that have been accepted by the great ācāryas. These scriptures are not products of the modes of passion and ignorance. Learned scholars and brāhmaṇas therefore always refer to them as sātvata-saṁhitās. The original speaker of these scriptures is Nārāyaṇa, the Supreme Personality of Godhead. This is especially mentioned in the Mokṣa-dharma (349.68), which is part of the Śānti-parva of the Mahābhārata. Liberated sages like Nārada and Vyāsa, who are free from the four defects of conditioned souls, are the propagators of these scriptures. Śrī Nārada Muni is the original speaker of the Pañcarātra-śāstra. (Sri Caitanya Caritamrta 1.5.41)
The theology of the Pancharatra is solely focused on the Personality of Godhead. The texts describe the appearance and character of the Lord, and the many avatars He takes for functions such as creation of the world and deliverance of the conditioned souls. It also describes methods of ritual worship, prayer and the employment of mantras.
When Narada Muni visited his disciple Srila Vyasadeva, he told him that although he’d compiled so much Vedic literature, he had not yet composed the ‘spotless glories of the Supreme Lord.’ So the great rishi set about writing the Bhagavata Purana, or Srimad Bhagavatam. Its 18,000 verses in 350 chapters all tell of the Lord and His devotees, with a full ninety chapters entirely dedicated to the accounts of Krishna’s appearance and activities in the world. In the 11th book of that great work is described what took place when the Supreme Lord Krishna was about to leave the world and return to His eternal abode. Krishna gave His parting instructions to His friend Uddhava, a conversation which is now recorded in the section known as the Uddhava Gita. In chapter 27 the Lord also explains Pancharatra worship.
Mantra (sacred sound) Yantra (sacred geometry) and Tantra (sacred ritual) are all part of the teaching found in the Pancharatra.
Chaitanya Mahaprabhu asked his close follower Sanatana Goswami to compile a handbook for Vaishnava life. The book was to describe everything from the daily activities of a devotee through to temple worship and the celebration of festivals. So with help from the revered Gopala Bhatta Goswami, who’d spent his youth and education as a priest in Sri Rangam, a temple town in southern India, he collected verses from some two hundred scriptures, including twenty-five selections from Pancharatra sources. From this effort was born the manual Hari-Bhakti-Vilasa.
Srila Rupa Goswami also gives credit to the Pancharatra as being one of the legitimate sources of conclusive evidence on the nature of Godhead and the methods of developing our relationship with God. Again, Srila Prabhupada writes:
Śrīla Rūpa Gosvāmī has said in the Bhakti-rasāmṛta-sindhu (1.2.101):
aikāntikī harer bhaktir utpātāyaiva kalpate
He clearly mentions in this verse that one must refer to the Vedic literatures and other, supplementary literatures and follow the conclusion of the Vedas. An invented devotional attitude simply creates disturbances in the transcendental realm.
Since the Pancharatra scriptures give directions for the worship of the Lord, particularly in deity worship, and since many of the ancient mantras have been included in the Hari Bhakti Vilasa, they can still be found being chanted today by all members of the Vaishnava sampradayas, including the members of ISKCON.