Al-Kāfi - Volume 3 > Causes of Death and that Believing People May Die by any Manner of Dying
Hadith #2

2ـ مُحَمَّدُ بْنُ يَحْيَى عَنْ أَحْمَدَ بْنِ مُحَمَّدِ بْنِ عِيسَى عَنِ ابْنِ فَضَّالٍ عَنْ عَاصِمِ بْنِ حُمَيْدٍ عَنْ سَعْدِ بْنِ طَرِيفٍ عَنْ أَبِي جَعْفَرٍ (عَلَيْهِ الْسَّلام) قَالَ كَانَ النَّاسُ يَعْتَبِطُونَ اعْتِبَاطاً فَقَالَ إِبْرَاهِيمُ (عَلَيْهِ الْسَّلام) يَا رَبِّ لَوْ جَعَلْتَ لِلْمَوْتِ عِلَّةً يُعْرَفُ بِهَا وَيُسَلَّى عَنِ الْمُصَابِ فَأَنْزَلَ الله عَزَّ وَجَلَّ الْمُومَ وَهُوَ الْبِرْسَامُ ثُمَّ أَنْزَلَ الدَّاءَ بَعْدَهُ.

2. Muhammad ibn Yahya has narrated from Ahmad ibn Muhammad ibn ‘Isa from ibn Faddal from ‘Asim ibn Humayd from Sa‘d ibn Tarif who has said the following: “Abu Ja’far, ‘Alayhi al-Salam, has said, ‘People would just drop dead. Ibrahim (Abraham), ‘Alayhi al Salam, pleaded before Allah, ‘Would that You had created a cause for death to be recognized thereby and for grieving people to receive condolence.’ Allah, the Majestic, the Glorious, then sent al-Mum, which is a kind of fever causing hallucination and thereafter He sent medicine.”