Sahih al-Bukhari 6350
Narrated Qais:
I came to Khabbab who had been branded with seven brands over his `Abdomen, and I heard him 
saying, "If the Prophet: had not forbidden us to invoke (Allah) for death, I would have invoked Allah 
for it."
حَدَّثَنَا مُحَمَّدُ بْنُ الْمُثَنَّى، حَدَّثَنَا يَحْيَى، عَنْ إِسْمَاعِيلَ، قَالَ حَدَّثَنِي قَيْسٌ، قَالَ أَتَيْتُ خَبَّابًا وَقَدِ اكْتَوَى سَبْعًا فِي بَطْنِهِ فَسَمِعْتُهُ يَقُولُ لَوْلاَ أَنَّ النَّبِيَّ صلى الله عليه وسلم نَهَانَا أَنْ نَدْعُوَ بِالْمَوْتِ لَدَعَوْتُ بِهِ‏.‏