Note: This side-quest is first available when you visit Westcliff for the first time.
Enter the temple of light and approach the small alter in front of the monk at the back of the room. Use it to make a donation to the temple. Give them about 1,000 gold. The monk will then tell you that if you donate a large sum of money when the Sun reaches its zenith, you may be rewarded.
Check your pause screen to track the time, and when it reaches somewhere between 12:00pm and 1:00pm, use the altar once again and donate around 10,000 gold pieces for your big reward.
Note: for completing this quest you will earn the following reward/s:
- Legendary Weapon: The Rising Sun (Cleaver)