Sahih al-Bukhari 4450
Military Expeditions led by the Prophet (pbuh) (Al-Maghaazi)
The sickness of the Prophet (ﷺ) and his death
Narrated `Urwa: `Aisha said, "Allah's Messenger (ﷺ) in his fatal illness, used to ask, 'Where will I be tomorrow? Where will I be tomorrow?", seeking `Aisha's turn. His wives allowed him to stay wherever he wished. So he stayed at `Aisha's house till he expired while he was with her." `Aisha added, "The Prophet (ﷺ) expired on the day of my turn in my house and he was taken unto Allah while his head was against my chest and his saliva mixed with my saliva." `Aisha added, "Abdur-Rahman bin Abu Bakr came in, carrying a Siwak he was cleaning his teeth with. Allah's Messenger (ﷺ) looked at it and I said to him, 'O `AbdurRahman! Give me this Siwak.' So he gave it to me and I cut it, chewed it (it's end) and gave it to Allah's Messenger (ﷺ) who cleaned his teeth with it while he was resting against my chest."