Bukhari

Hadith Commentary:
From this hadith, it is established that one may take and use another person’s miswak (tooth-stick), and it is also established that a person may chew the miswak in his own mouth and then give it to his brother. Furthermore, it is proven that, in times of need, one may request something necessary from a brother in whom one has trust and confidence.
This is the very meaning of mutual cooperation.
This hadith also establishes the virtue of Aisha (radi Allahu anha), as she was honored with the special service of the Prophet (sallallahu alayhi wa sallam) during his final illness.
May Allah’s curse be upon those ill-natured people who, by using insolent words regarding the noble status of Aisha as-Siddiqah (radi Allahu anha), ruin their own hereafter.

Hadith Commentary:
(1)
The intention of Imam Bukhari rahimahullah is that the use of the tooth-stick (miswak) is necessary on the day of Jumu‘ah (Friday).
If one does not have it with oneself, then one may use another person’s miswak with their permission.
This hadith also proves that there is no objection in using a miswak that has already been used by someone else. Furthermore, it is also understood that, as an act of cooperation, one may soften the miswak for another person.
‘Allamah ‘Ayni rahimahullah has written that Imam Bukhari rahimahullah’s objective is to mention the purity of saliva, but its proper place is in the Book of Ablution (Kitab al-Wudu’).

(2)
From another narration, it is known that ‘A’ishah radi Allahu anha took the miswak from her brother ‘Abd al-Rahman radi Allahu anhu and gave it to the Messenger of Allah sallallahu alayhi wa sallam, but due to the weakness from illness, he felt difficulty in using the miswak.
‘A’ishah radi Allahu anha said, “Shall I soften it for you?”
Then ‘A’ishah radi Allahu anha bit off and discarded the hard fibers of the miswak with her teeth and chewed it herself to soften it. After that, the Messenger of Allah sallallahu alayhi wa sallam used it.
When the Messenger of Allah sallallahu alayhi wa sallam finished with the miswak, he pointed upwards with the finger of his hand.
After that, he entrusted his soul to the Creator of souls.
‘A’ishah radi Allahu anha says that in this way, Allah Ta‘ala created a means for the mingling of my saliva and the saliva of the Messenger of Allah sallallahu alayhi wa sallam on the last day of this world and the first day of the Hereafter.
(Sahih al-Bukhari, al-Maghazi, Hadith: 4449)