Mu'jam Kabir Tabarani 12971 — concerning this saying of Allah

Sayyiduna Ibn Abbas (may Allah be pleased with them both) said concerning this saying of Allah Almighty: "Those who, when a calamity strikes them, say: Indeed we belong to Allah, and indeed to Him we will return. It is they upon whom are blessings from their Lord and mercy, and it is they who are the rightly guided" [Surah al-Baqarah: 157]: Allah, the Mighty and Majestic, has informed us that when the believer submits to the command of Allah and turns back to Him by saying "Inna lillahi wa inna ilayhi raji'un (We belong to Allah and to Him we return)" at the time of a calamity, three good things are written for him: blessing (salah), mercy, and success on the path of guidance. And the Messenger of Allah (peace and blessings be upon him) said: "Whoever says the istirja' at the time of a calamity (that is, says Inna lillahi wa inna ilayhi raji'un), Allah will compensate him for his calamity, make his outcome better, and grant him a good replacement with which he will be pleased."