When the pangs of death started, ‘Aishah leant him against her. She used to say: One of Allah’s bounties upon me is that the Messenger of Allâh died in my house, while I am still alive. He died between my chest and neck while he was leaning against me. Allâh has mixed his saliva with mine at his death. For ‘Abdur Rahman – the son of Abû Bakr – came in with a Siwak (i.e. the root of a desert plant used for brushing teeth) in his hand, while I was leaning the Messenger of Allâh against me. I noticed that he was looking at the Siwak, so I asked him – for I knew that he wanted it — “Would you like me to take it for you?” He nodded in agreement. I took it and gave it to him. As it was too hard for him, I asked him “Shall I soften it for you?” He nodded in agreement. So I softened it with my saliva and he passed it (on his teeth).
In another version it is said: “So he brushed (Istanna) his teeth as nice as he could.” There was a water container (Rakwa) available at his hand with some water in. He put his hand in it and wiped his face with it and said:
“There is no god but Allah. Death is full of agonies.” [Sahîh al-Bukhârî, 2/640]
Reference: A friend of mine sent me this. I don’t remember the source.