According to a myth, once Narada Muni’s meditation could not be disturbed even by Kamdev, the god of love. Narada Muni overheard someone say that this made him bigger than even Lord Shiva, since Kamdev had managed to disturb Shiva and his meditation was disturbed by him. This comment went to Narada’s head and he started believing that he was superior to Lord Shiva.
Since Lord Vishnu was concerned of his favourite disciple’s pride and arrogance, he decided to teach Narada a lesson in humility. Vishnu requested his consort, Goddess Lakshmi to take the human form of Srimati, the beautiful daughter, of King Ambarish. During one such visit to the King Ambarish’s palace, Narada saw Srimati and instantly fell in love with her and expressed his desire to marry Srimati. King Ambarish though did not prefer the match, could not say anything to Narada. So he agreed to host a swayamwara and let Srimati choose her husband.
Narada immediately went to Lord Shiva and asked him as to what should he do, so that Srimati selected him. Shiva said that if he could look as handsome as Vishnu, then, Srimati might notice him and for this he should meet Vishnu himself. Narada went to Vishnu and requested that he look as good as Vishnu to enable Srimati select him. Vishnu smiled and decided to play a trick on Narada.
On the day of the swayamvara, Narada got a monkey-face, without his realising this. When Srimati came with a garland in her hand, she saw no Narada Muni but a monkey-faced man. However, next to him was a handsome man calling her out. Srimati immediately garlanded him and before anybody could realise, both Srimati and the handsome man (who was none other than Lord Vishnu) had vanished in thin air.
When Narada saw his reflection in water, he was angry and felt cheated. He then cursed Vishnu that a time would come, when he too would have to be separated from his love, and at that time, it would be a monkey, whose help he would have to take to get his love back! I will spare you all the story of Ramayana!
However, Narada had also learnt his lesson and since then he shed all his pride and arrogance and decided to remain unmarried. Because of this episode, Narada Muni is also referred to as Kapi-Vaktra or monkey-faced.