Who is Narada muni?
Narada Muni is the pure devotee of Lord Vishnu i.e Krishna. He is mentioned in most of the Vedic literarures, especially puranas. He travels from one place to another in the space and teaches the valueof devotional service of the Lord.
Srila Prabhupada in his Bhagavatam purport writes about Narada Muni as follows:Narada Muni: is inevitably associated with the narrations of the Puranas. He is described in the Bhagavatam. In his previous life he was the son of a maidservant, but by good association with pure devotees he became enlightened in devotional service, and in the next life he became a perfect man comparable with himself only. In the Mahavarata his name is mentioned in many places. He is the principle devarsi, or the chief sage amongst the demigods. He is the son and disciple of Brahmaji, and from him the disciplic succession in the line of Brahma has been spread. He initiated Prahlada Maharaja, Dhruva Maharaja and many celebrated devotees of the Lord. He initiated even Vyasadeva, the author of the Vedic literatures, and from Vyasadeva, Madhvacarya was initiated, and thus the Madhva-sampradäya, in which the Gaudiya-sampradaya is also included, has spread all over the universe. Çré Caitanya Mahäprabhu belonged to this Madhva-sampradaya; therefore, Brahmaji, Narada, Vyasa, down to Madhva, Caitanya and the Goswami all belonged to the same line of disciplic succession. Naradaji has instructed many kings from time immemorial. In the Bhagavatam we can see that he instructed Prahlada Maharaja while he was in the womb of his mother, and he instructed Vasudeva, father of Krishna, as well as Maharaja Yudhisthira.