Location: Shaolin Temple
Prerequisite: Complete Joining Wudang
Petitioner: Hui Da
Reward: 500 coins
The only obstruction to beginning this side quest is finding the Shaolin Temple. If you leave Wutong Village and head east / northeast you'll soon run into Yanfu Town. Northeast of here, across a bridge, you'll find Shaolin Temple atop a mountain. You won't be able to enter the temple until you've joined Wudang Sect and Yi has changed his clothes.
The petitioner, a monk named Hui Da, is standing near the living quarters in the northeast of Shaolin Temple's Rear Hall, in the north of the temple. Check the right side of the lower house to find him. Hui Da has no interest in martial arts, and spends his days cleaning the temple. He has a love of music, however, and would like a Dragon Neck Flute. Better oblige him.
Leave Shaolin Temple and travel back west, towards Wutong Village. Southwest of Wutong is Pingkang City. Enter, then travel as far to the west as you can go. Here you'll find a Pawnshop. A Dragon Neck Flute will cost you 1,000 coins. Take it back to Hui Da to receive your reward, as well as an Affinity boost with the budding musician. You'll be seeing him again, if you decide to raise your Affinity further with Hui Da.