What had the man sworn?
The man in the story "Three Questions" had sworn to kill the person who had killed his brother. This oath had consumed his thoughts and actions, leading him to seek the advice of a wise hermit to find answers to his three questions.

Explanation in detail:
- Background: The man had a deep-seated desire for revenge against his brother's killer, and this desire had clouded his judgment and consumed his thoughts.
- Seeking answers: In his quest for answers, he sought the help of a wise hermit who resided in a far-off land.
- Three questions: The man had three questions for the hermit: What is the right time to begin something? Who are the most important people to listen to? And, what is the most important thing to do?
- Hermit's response: The hermit's responses to the man's questions challenged his preconceived notions and forced him to reflect on his priorities and values.
- Realization: Through his interactions with the hermit, the man came to realize the futility of his oath of vengeance and the importance of forgiveness and compassion.
In conclusion, the man had sworn to kill his brother's killer, but through his encounter with the wise hermit and the reflection on his three questions, he learned valuable lessons about the true meaning of life and the importance of forgiveness.