Sahih Bukhari Volume 007, Book 062, Hadith Number 144.
Narrated By 'Aisha : That during his fatal ailment, Allah's Apostle, used to ask his wives, "Where shall I stay tomorrow? Where shall I stay tomorrow?" He was looking forward to 'Aisha's turn. So all his wives allowed him to stay where he wished, and he stayed at 'Aisha's house till he died there. 'Aisha added: He died on the day of my usual turn at my house. Allah took him unto Him while his head was between my chest and my neck and his saliva was mixed with my saliva.