:salamext:
Qur'an 2:155
And certainly, We shall test you with something of fear, hunger, loss of wealth, lives and fruits, but give glad tidings to As-Sabirin (the patient ones, etc.).
الَّذِينَ إِذَا أَصَابَتْهُم مُّصِيبَةٌ قَالُواْ إِنَّا لِلّهِ وَإِنَّـا إِلَيْهِ رَاجِعونَ
156: Who,
when afflicted with calamity, say:
"Truly! To Allah we belong and truly, to Him we shall return." (innaa lillahi wa ina alayhi raji'un)
أُولَـئِكَ عَلَيْهِمْ صَلَوَاتٌ مِّن رَّبِّهِمْ وَرَحْمَةٌ وَأُولَـئِكَ هُمُ الْمُهْتَدُونَ 157:
They are those on whom are the Salawat (i.e. blessings, etc.) (i.e. who are blessed and will be forgiven) from their Lord, and (they are those who) receive His Mercy, and it is they who are the guided-ones.
So whenever you face a calamity/hardship/trial, or remember one - you should say it, and there is reward in that insha Allah.