I asked the Messenger of Allah ﷺ about sudden death, and he said, "It is a relief for the believer and a grievous seizure for the wicked."
حدثنا وكيع حدثنا عبيد الله بن الوليد عن عبد الله بن عبيد بن عمير
سألت رسول الله ﷺ عن موت الفجأة فقال راحة للمؤمن وأخذة أسف لفاجر
No references are available.
Its chain of transmission is sahih, and it has already been mentioned, and it is in the Sahihs.