Sahih al-Bukhari Book 75, Hadith 27
I visited the Prophet (ﷺ) while he was having a high fever. I touched him an said, "You have a very high
fever" He said, "Yes, as much fever as two me of you may have." I said. "you will have a double
reward?" He said, "Yes No Muslim is afflicted with hurt caused by disease or some other
inconvenience, but that Allah will remove his sins as a tree sheds its leaves."
`Aisha, (complaining of headache) said, "Oh, my head"! Allah's Messenger (ﷺ) said, "I wish that had happened while I was still living, for then I would ask Allah's Forgiveness for you and invoke Allah for you." Aisha said, "Wa thuklayah! By Allah, I think you want me to die; and If this should happen, you would spend the last part of the day sleeping with one of your wives!" The Prophet (ﷺ) said, "Nay, I should say, 'Oh my head!' I felt like sending for Abu Bakr and his son, and appoint him as my successor lest some people claimed something or some others wished something, but then I said (to myself), 'Allah would not allow it to be otherwise, and the Muslims would prevent it to be otherwise".
Allah's Messenger (ﷺ) came to visit me during my ailment which had been aggravated during Hajjat-al- Wada`. I said to him, "You see how sick I am. I have much property but have no heir except my only daughter May I give two thirds of my property in charity?"! He said, "No." I said, "Half of it?" He said, "No." I said "One third?" He said, "One third is too much, for to leave your heirs rich is better than to leave them poor, begging of others. Nothing you spend seeking Allah's pleasure but you shall get a reward for it, even for what you put in the mouth of your wife."