Sahih Muslim Book - 48, Hadith - 6814

حَدَّثَنَا زُهَيْرُ بْنُ حَرْبٍ ، حَدَّثَنَا إِسْمَاعِيلُ ، يَعْنِي ابْنَ عُلَيَّةَ ، عَنْ عَبْدِ الْعَزِيزِ ، عَنْ أَنَسٍ ، قَالَ: قَالَ رَسُولُ اللهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ : لاَ يَتَمَنَّيَنَّ أَحَدُكُمُ الْمَوْتَ لِضُرٍّ نَزَلَ بِهِ ، فَإِنْ كَانَ لاَ بُدَّ مُتَمَنِّيًا فَلْيَقُلْ : اللَّهُمَّ أَحْيِنِي مَا كَانَتِ الْحَيَاةُ خَيْرًا لِي ، وَتَوَفَّنِي إِذَا كَانَتِ الْوَفَاةُ خَيْرًا لِي.

It was narrated from Anas that the Messenger of Allah (s.a.w) said: "None of you should wish for death because of some harm that has befallen him. If he must wish for it, then let him say: 'O Allah, keep me alive so long as living is good for me, and cause me to die when death is good for me.'"