A childless person went to many doctors for treatments. The treatments were extremely painful, but all his attempts proved futile. One year, he came to his rebbe, and he begged him to bless him with children. It was then Slichos, and he was hoping that that he could yet merit a child in the coming year.
The Rebbe replied, “If I tell you the name of a tzaddik who has the ability to bless you with children, will you go to him?” “Certainly,” the chassid replied.
“And if the tzaddik requests something very difficult from you, will you do as he advises?”
“Of course I will,” the man replied. “I’ll do whatever I can to have children.” The Rebbe said, “Well, there was a tzaddik many years ago, renowned as the Tosfos Yom Tov zt’l. He blesses all people who don’t speak by the davening to have children. I advise you to follow the Tosfos Yom Tov’s counsel. Be cautious, don’t speak during the tefillah, and you will receive the brachah from the Tosfos Yom Tov, and you will merit healthy children.”
He followed the counsel. A year later, around Selichos time, he had twins. He said, “The doctors gave me painful treatments, but nothing was as hard as remaining silent during the tefillah. It was especially difficult when someone came over and wanted to speak with me. My face changed colors, as I would motioned to them that I can’t speak until after the tefillah…” He passed the difficult test, received the Tosfos Yom Tov’s blessing, and had children. ~ R’ Elimelech Biderman Shlita
The Tosfos Yom Tov further promises that one who does not talk during davening will be subject to all the blessings in the Torah, will be saved from illness, have healthy children who are Torah observant, who will get married, do good deeds and always serve Hashem truthfully.