The Baal Shem Tov's Seder in Constantinople

The holy Baal Shem Tov is traveling to the Holy Land when he must stop in Constantinople with his daughter Udel for Pesach. During the seder, the Baal Shem Tov recites the verse "To He Alone who performs great miracles" with tremendous feeling. Later, their host asks the reason for this and discovers that a miracle had indeed happened at that moment, saving the Jews of the city from a calamity.