Fatimah bint Husayn (may Allah have mercy on her) narrates from her father, Sayyiduna Husayn bin Ali (may Allah be pleased with him), that the Prophet (peace and blessings be upon him) said: "Whoever is struck by a calamity, and then whenever he remembers it he says: Inna lillahi wa inna ilayhi raji'un (We belong to Allah and to Him we return), Allah will renew for him a reward for it equal to what he had on the day it struck him."
Hadith Referenceالمعجم الكبير للطبراني / باب الحاء / 2882