Rashi states: “Why did (the Torah) see fit to mention it here? It is to teach us that annulment of vows may be performed by a single expert.”
Sefer M’Oran Shel Yisroel relates a story regarding the annulment of vows in the name of the Kli Chemdah zt”l, who heard it from the Maharil Diskin zt”l, who heard it from his father, Rav Binyomin zt”l, the Rov of Lomzha, in whose times the story occurred:
A great talmid chochom settled in Lomzha and spent all day and night learning non-stop in the bais medrash. His love of Torah was so great that he made a ‘neder’ to remain in the bais medrash for many days without leaving for any reason. Local residents would bring him food and drink and took care of his other needs. However, since there was no eruv in the city, they couldn’t bring him food on Shabbos. This caused him a lot of anguish. He wanted to annul his vow but he couldn’t find a way to do it.
One day, Rav Akiva Eiger zt”l arrived in Lomzha to attend a chasuna. Rav Binyomin, the Rov of the city, welcomed the distinguished guest warmly. As they engaged in conversation, he mentioned the problem this talmid chochom had. Rav Akiva Eiger said that he wanted to go to the bais medrash to meet him. Of course, Rav Binyomin accompanied him, and many others trailed behind them to see what would happen.
Rav Akiva Eiger entered the bais medrash and walked over to the talmid chochom, who was bent over his sefarim. He told him, “I heard that you are a great Torah scholar. Since you cannot leave the bais medrash, I came to meet you here.”
When the talmid chochom saw that the greatest Gaon of the generation had come to visit him, he was awestruck. He said, “Why should such a great man like yourself need to bother himself to visit me? I feel so bad for troubling you!”
Rav Akiva then asked him, “If you had known that your vow would cause this trouble for me, would you have made the neder?”
The talmid chochom answered that he definitely would have not. Rav Akiva Eiger responded, “Mutar lach. Mutrach lach...” In his great wisdom, he had found a “pesach of charatah.” He had found a way to make the man regret ever making the vow, which serves to annul it.
