Hadith: Abdur-Rahmān ibn Abi Bakr visited the Prophet (may Allah's peace and blessings be upon him) as I had the Prophet's head reclined on my chest. ‘Abdur-Rahmān (may Allah be pleased with him) had a fresh tooth-stick and was brushing his teeth with. The Messenger kept his eye on it

عن عائشة رضي الله عنها قالت: ((دخل عبد الرحمن بن أبي بكر الصديق رضي الله عنهما على النبي صلى الله عليه وسلم وأنا مُسْنِدَتُه إلى صدري، ومع عبد الرحمن سِواك رَطْب يَسْتَنُّ به، فأَبَدَّه رسول الله صلى الله عليه وسلم بَصَره، فَأَخَذْتُ السِّوَاك فَقَضَمتُه، فَطَيَّبتُه، ثُمَّ دَفَعتُهُ إلى النبي صلى الله عليه وسلم فَاسْتَنَّ به فما رأيتُ رسول الله صلى الله عليه وسلم استَنَّ اسْتِنَانًا أَحسَنَ منه، فَما عَدَا أن فَرَغَ رسول الله صلى الله عليه وسلم : رَفَع يَدَه -أو إصبعه-، ثم قال: في الرفيق الأعلى -ثلاثا- ثمَّ قَضَى، وكَانت تقول: مَاتَ بَينَ حَاقِنَتِي وَذَاقِنَتِي)).
[صحيح] - [رواه البخاري]

‘Ā'ishah (may Allah be pleased with her) reported: Abdur-Rahmān ibn Abi Bakr visited the Prophet (may Allah's peace and blessings be upon him) as I had the Prophet's head reclined on my chest. ‘Abdur-Rahmān (may Allah be pleased with him) had a fresh tooth-stick and was brushing his teeth with. The Messenger kept his eye on it, so I took the tooth-stick, gnawed it, freshened it, and then gave it to the Prophet (may Allah's peace and blessings be upon him). He brushed his teeth with it and I had never seen the Messenger brushing his teeth more beautifully. After finishing brushing his teeth, he lifted his hand, or his finger, and said three times: "To the Highest Companion." Then, he passed away." ‘Ā'ishah would say: "He died while his head was resting between my chest and chin."
[Authentic hadith] - [Narrated by Bukhari]

Explanation

‘Ā'ishah (may Allah be pleased with her) recalls a story that demonstrates how much the Prophet (may Allah's peace and blessings be upon him) loved the tooth-stick and how attached he was to it. That is to say that ‘Ā'ishah's brother ‘Abdur-Rahmān ibn Abi Bakr visited the Prophet (may Allah's peace and blessings be upon him) when he was near death. He had a fresh tooth-stick in his hand, which he was brushing his teeth with. When the Prophet (may Allah's peace and blessings be upon him) saw ‘Abdur-Rahmān with it, the sickness and pain he was experiencing did not distract him, because he liked it so much. He stared at the tooth-stick in ‘Abdur-Rahmān's hand as if he wanted it. ‘Ā'ishah realized that. So she took the tooth-stick from her brother, clipped off the top of the tooth-stick with her teeth, cleaned it and freshened it up and gave it to the Prophet (may Allah's peace and blessings be upon him) so he brushed his teeth with it. ‘Ā'ishah said that she had never seen anyone brush their teeth more beautifully than the way the Prophet did then. After he finished brushing his teeth, he raised his finger, affirming the oneness of Allah, and chose to go and meet his Lord, the Most High. Then, he passed away. ‘Ā'ishah (may Allah be pleased with her) was proud, and rightfully so, that the Prophet (may Allah's peace and blessings be upon him) passed away while his head was upon her chest.