Aishah narrated: "The Prophet of Allah ﷺ would clean his teeth with the Siwak, then he would give me the Siwak in order to wash it. So I would first use it myself, then wash it and return it.
Explanation & Benefits
Shaykh Umar Farooq Saeedi
Benefits and Issues:
➊ This highlights the legal (shar‘i) importance of purity and cleanliness, as the Prophet (sallallahu alayhi wa sallam) used to wash his miswak (tooth-stick) after use.
➋ The intention of Lady Aisha (radi Allahu anha) was to seek blessing (tabarruk) from the saliva of the Prophet (sallallahu alayhi wa sallam), which the Prophet (sallallahu alayhi wa sallam) affirmed. It should be noted that seeking blessing in this manner was exclusively specific to the person of the Prophet (sallallahu alayhi wa sallam) alone.
Source: Sunan Abu Dawood – Commentary by Shaykh Umar Farooq Saeedi, Page: 52