The residents of Kaliv once went to ask the Rebbe whom they should choose to serve as the chazan for the Yomim Noraim. He told them, ‐I will teach you how to choose a baal tefillah by telling you a story that happened to me.‑
He proceeded to relate:
I once came to a certain city close to Minchah time. I was very hungry and I saw that the residents of the city were preparing a seudah for after Maariv. I thought that I would wait until after Maariv and then eat with them. When the tzibur davened Maariv, they spent a very long time on the tefillah of Ahavas Olam. For two full hours they recited this prayer with utmost devotion and warmth. After davening, I asked them why they spent so much time on Ahavas Olam. They told me that my question would be answered during the seudah.
During the festive meal, they began to read the following story from the chronicles of the city:
Many years ago, the local government issued a decree to massacre all of the Jewish residents. There was one noblewoman who liked the Jews. She secretly went to the home of the Rosh Hakahal and warned him about the decree. Of course, the Jews engaged in much prayer and fasting. However, the shamash of the city, who was a wise and learned man, said, ‐The decree has not been annulled. I will tell you the reason for the decree. It is because the chazan for the Yomim Noraim was a sinful, decadent man. The way to cancel the decree is to do the Yomim Noraim over again. Therefore, we have to go back and start the month of Elul once more.‑
This occurred in the middle of the winter. With no other choice, the Jews began to do teshuva again, as if it were the beginning on Elul. They may have even said Selichos again (which was permitted due to the danger). They then observed Rosh Hashanah and Yom Kippur again. The baal tefillah was the shamash, who was a great man. On ‐Yom Kippur‑, every man, woman and child gathered in the shul. This very day was the one that the gentiles planned to murder every Jew, and they surrounded the bais knesses as the Jews prayed with devotion. When the davening ended, the shamash announced, ‐The decree has been rescinded.‑
At that moment, every gentile outside the shul went insane and they began to kill each other – and the Jews were left in peace.
When the Jews saw that they had been saved, they rose to daven Maariv with much joy. They were going to daven quickly, as is usually done at the end of a fast day, but the shamash said, ‐Don’t daven quickly. After such a Yom Kippur, you have to daven Maariv with kavanah!‑
The shamash again served as the chazan and, when he reached Ahavas Olam, everyone was overcome with d’veikus, and this tefillah took two full hours.
The Jews of the town then accepted to celebrate this day every year by reciting Ahavas Olam slowly and with devotion, and to then hold a festive seudah to commemorate the miracle.
The Kaliver Rebbe concluded, ‐You can see from this story how important it is to have a proper chazan for the Yomim Noraim!‑