Sage Durvasa is known for his curses. But there were times, when he was helpless before the power of a humble of follower of Lord Vishnu. One such instance was of Ambarisha. The full story goes as:
Ambarisha was a king and he was deeply into following Lord Vishnu. He and his queen used to observe various fasts over the year. On second day of Ekadashi, Ambarish had to end his fast. On that very day, Sage Durvasa paid a visit to Ambarisha.
Sage Durvasa got angry with Ambarisha for petty reason and Ambarish resigned to his fate with folded hands. But nothing happens to a person, who is helped by the Lord himself. Lord Vishnu sends his sudarshan chakra to safeguard Ambarish.