Qran 2, 155-157 And We will surely test you with something of fear and hunger and a loss of wealth and lives and fruits, but give good tidings to the patient. 156 Who, when disaster strikes them, say, “Indeed we belong to ALLAH, and indeed to Him we will return.” 157 Those are the ones upon whom are blessings from their LORD and mercy. And it is those who are the [rightly] guided.

Arabic

155 وَلَنَبْلُوَنَّكُمْ بِشَيْءٍ مِّنَ ٱلْخَوْفِ وَٱلْجُوعِ وَنَقْصٍ مِّنَ ٱلأَمَوَالِ وَٱلأَنفُسِ وَٱلثَّمَرَاتِ وَبَشِّرِ ٱلصَّابِرِينَ 

156 ٱلَّذِينَ إِذَآ أَصَابَتْهُم مُّصِيبَةٌ قَالُواْ إِنَّا للَّهِ وَإِنَّـآ إِلَيْهِ رَاجِعُونَ

157 أُولَـٰئِكَ عَلَيْهِمْ صَلَوَاتٌ مِّن رَّبِّهِمْ وَرَحْمَةٌ وَأُولَـٰئِكَ هُمُ ٱلْمُهْتَدُونَ

Commentary

v. 155 Surely GOD will test you with tribulations, frightened by an enemy, threatened by hunger, or perhaps because of drought and the diminution of your possessions, or because of the departure to another Life of people dear to you, but this does not come to the believer as a punishment, but only to fortify and to see if you practice patience and acceptance of events. The Good Tidings of the future for the righteous and of Paradise will come to those who show patience during calamities.
v. 156 Those who when afflicted by an affliction or calamity say “Surely we belong to GOD, and we are His possession, and being His trusting servants He does what He wants to us because He comes for our ultimate good. Only to Him (GOD) will we return to go to the Hereafter where He will reward us.
In a hadīth it is said that whoever pronounces this formula “surely we belong to GOD and to Him we will return” when an affliction strikes him, GOD will reward him and with something even better.
v. 157 On such women and men will descend the blessings, forgiveness and grace of their LORD’s mercy and always those will be guided to the Truth in righteousness.