The Book of Zuhd and Softening of Hearts
Ṣaḥīḥ Muslim 7500
عَجَبًا لأَمْرِ الْمُؤْمِنِ إِنَّ أَمْرَهُ كُلَّهُ خَيْرٌ وَلَيْسَ ذَاكَ لأَحَدٍ إِلاَّ لِلْمُؤْمِنِ إِنْ أَصَابَتْهُ سَرَّاءُ شَكَرَ فَكَانَ خَيْرًا لَهُ وَإِنْ أَصَابَتْهُ ضَرَّاءُ صَبَرَ فَكَانَ خَيْرًا لَهُ
ʿajaban lʾamri al-muʾmini inna amrah kullah khayrun walaysa dhāka lʾaḥadin illā lilmuʾmini in aṣābathu sarrāʾu shakara fakāna khayran lah wa-in aṣābathu ḍarrāʾu ṣabara fakāna khayran lah
Transliteration generated from the Arabic vowel marks
The full narration
Suhaib reported that Allah's Messenger (ﷺ) said:Strange are the ways of a believer for there is good in every affair of his and this is not the case with anyone else except in the case of a believer for if he has an occasion to feel delight, he thanks (God), thus there is a good for him in it, and if he gets into trouble and shows resignation (and endures it patiently), there is a good for him in it
Source
Ṣaḥīḥ Muslim · 7500