Sahih Bukhari
One-fifth of Booty to the Cause of Allah (Khumus)
Volume: 004 / Book Number: 053 / Hadith Number: 331
Narrated 'Aisha:
(the wife of the Prophet) When the sickness of Allah's Apostle got aggravated, he asked the permission of his wives that he should be treated in my house, and they permitted him.