Sunan Ibn Majah, Volume 5, Book 36, Hadith 4031 (DarusSalam)

It was narrated from Anas bin Malik that the Messenger of Allah said: “The greatest reward comes with the greatest trial. When Allah loves a people He tests them. Whoever accepts that wins His pleasure but whoever is discontent with that earns His wrath.”

حَدَّثَنَا مُحَمَّدُ بْنُ رُمْحٍ، أَنْبَأَنَا اللَّيْثُ بْنُ سَعْدٍ، عَنْ يَزِيدَ بْنِ أَبِي حَبِيبٍ، عَنْ سَعْدِ بْنِ سِنَانٍ، عَنْ أَنَسِ بْنِ مَالِكٍ، عَنْ رَسُولِ اللَّهِ ـ صلى الله عليه وسلم ـ أَنَّهُ قَالَ ‏ "‏ عِظَمُ الْجَزَاءِ مَعَ عِظَمِ الْبَلاَءِ وَإِنَّ اللَّهَ إِذَا أَحَبَّ قَوْمًا ابْتَلاَهُمْ فَمَنْ رَضِيَ فَلَهُ الرِّضَا وَمَنْ سَخِطَ فَلَهُ السُّخْطُ ‏" ‏ ‏.‏

sunnah.com