Rav Chaim Volozhin's Purim Secret From A Mysterious Guest
One Purim an old man appeared at Rav Chaim Volozhin's Purim seuda. Rav Chaim gave him a coin for tzedaka. The old man then said that if he gives him another coin, he will tell him a Chiddush in the Megila. Rav Chaim agreed and the old man asked a question.
The Medrash says that after the gezeira of Haman, Moshe Rabbeinu told Eliyahu HaNavi to go tell Mordechai to daven on earth while they will daven in Shamayim. Eliyahu told Moshe that he already saw that the gezeira was signed and sealed in Shamayim so there was no chance of salvation. Moshe asked, was the seal made out of earth or blood. Eliyahu said it was out of earth. In that case said Moshe Rabbeinu there is still hope.
Where, asked the old man, do we see in the Megila that the seal was not from blood? Rav Chaim didn't answer and the old man continued. The Megila says that Haman plotted to destroy the Yehudim, "U'Liabdam". If you break the word U'Liabdam into two words it says "V'Lo B'Dam", the decree was not sealed in blood.
Rav Chaim was so excited about this answer that when he went to visit his Rebbi the Vilna Gaon, he repeated it to him. The Vilna Gaon also became emotional upon hearing this and told Rav Chaim that the "old man" was none other than the old man who revealed this secret over 2,000 years ago during the story of Purim. It was Eliyahu HaNavi himself.
Source: Revach L'Neshama