Ayatullah Haj Shaikh Abdul Karim Haaeri Yazdi (founder of the Hauze-Ilmiyya in Qom) narrates, ‘It was the period of my education in the Hauze Ilmiyya in Samarra. There was an epidemic in the city that had taken in its wake many victims. One day, all the scholars had assembled at Ayatullah Sayyed Muhammad Fasharki (r.a.)’s residence, the latter being my teacher. Then unexpectedly, Ayatullah Mirza Muhammad Taqi Shirazi (r.a.) entered the house. His stature was no less than that of Ayatullah Fasharki (r.a.). There was a round of general discussion and the scholars started deliberating on the epidemic and how at the rate it was claiming lives, it would very soon wipe out the entire city. In the midst of this discussion Ayatullah Fasharki (r.a.) rose, and asked, ‘Do you all acknowledge me as the Mujtahid? Then If I impose a decree upon you, will you act according to it?’ We all replied emphatically, ‘Yes! Indeed you are the Mujtahid.’ Then Ayatullah Fasharki (r.a.) addressed the audience and declared, ‘I command the Shias of Sammarah to recite Ziarate Ashoora for a
period of ten days. Then offer the reward of this recitation to the mother of Imame Zamaana (may our souls be sacrificed for him), Janabe Nargis Khatoon (s.a.). Then beseech her to present our case to her son Hazrat Valiul Asr, so that Imam (a.s.) shields us from the malady.’
Ayatullah Fasharki (r.a.) relates further, ‘I assure the person security from the plague, if he recites Ziarate Ashoora.’ Since it was a matter of life and death, the entire Shia population followed Ayatullah Fasharki’s recommendation and began reciting this Ziarat. Miraculously, with the recitation of the Ziarat, the plague subsided and the mo’mineen were spared. But this phenomenon was observed only among the Shias, as the Ahle Sunnah continued to fall prey to this malady. Everyday, the plague claimed at least one from the Ahle Sunnah. They were defenseless, as this ailment was without a cure. Before long, they realized that the plague was claiming only their members, while the Shias were somehow reprieved. In order to hide their embarrassment, they started conducting the burial of their dead in the middle of the night. When one of the Ahle Sunnah inquired from the Shias, the reason behind their miraculous reprieve, the latter revealed their secret of Ziarate Ashoora. Then the Ahle Sunnah too undertook recitation of this Ziarat. And this Ziarat’s enigmatic prowess was manifested when they also started receiving respite from the dreaded plague. In fact, some of them used to visit the shrines of Imam Ali Naqi (a.s.) and Imam Hasan Askari (a.s.) and began confessing: ‘We recite the very Ziarat for you that is recited by your Shias.’
Shaykh Abdul Kareem (r.a.) observes that on reciting this Ziarat, Shias and Ahle Sunnah both became immune to this plague.