A hadith and commentary.
The Prophet, peace and blessings of Allah be upon him, said:
"Were it not that I might burden my Ummah,"
"I would have commanded them to use the siwak with every ablution."
Commentary:
Using the siwak at the time of ablution is a Sunnah.
To those who practice it:
One of the ways to remember it
is to place the siwak near the place of ablution.
So, when a person intends to perform ablution,
he uses the siwak during the ablution,
in order to attain the reward of obeying the Prophet, peace be upon him,
and implementing his Sunnah.