Commentary of Hadith 2999 (Sahih Muslim)

On the authority of Suhaib (may Allaah be pleased with him) he said: The Prophet (sallallaahu alayhi wa sallam said: 
“Amazing is the affair of the believer, verily all of his affair is good and this is not for no one except the believer. If something of good/happiness befalls him he is grateful and that is good for him. If something of harm befalls him he is patient and that is good for him” (Saheeh Muslim #2999)