The Tefillah Against Talking in Shul

During the pogroms of 5408 and 5409, the Tosafos Yom Tov fasted and begged to be shown why such a calamity had struck. It was revealed that idle chatter during davening had damaged the letter vav, so that dibur became dever. He then composed (others say the Maharal composed it, and he instituted its recitation in his kehillos) a special tefillah on the power of silence and the harm of talking in shul. It is printed in many siddurim next to the Mi Sheberach said on Shabbos after the Torah reading.