Answered by Shaykh Abul ‘Ataa Ahmad Banaja (may Allah preserve him)
Did the Prophet ﷺ used Siwak for cleanliness or there is reward for using it? As for cleanliness, does brushing teeth with brush and toothpaste enough or do we have to use Siwak to gain the reward for the Sunnah?
You must first understand the difference between, Siwak and Arak. Siwak is the act of brushing your teeth. Arak is the famous stick cut from the tree, which is used to brush the teeth. So, Siwak is the act of brushing teeth, be it with toothbrush and toothpaste, or with a harsh cloth and even for some scholars using only finger is also enough. But rather than generalizing the use of finger, it is better to say that, using (only) the finger (for Siwak) is when you don’t have any material to clean your teeth with, in which case you can do it with only finger also, and there should be water (in your mouth). The name Siwak has been referred to the stick overtime, making it easier to understand the act of brushing with the stick. Prophet ﷺ liked to do Siwak with the stick of Arak. It comes in a narration that ‘Aishah رضى الله عنها said:
تُوُفِّيَ النَّبِيُّ صلى الله عليه وسلم فِي بَيْتِي، وَفِي نَوْبَتِي، وَبَيْنَ سَحْرِي وَنَحْرِي، وَجَمَعَ اللَّهُ بَيْنَ رِيقِي وَرِيقِهِ. قَالَتْ دَخَلَ عَبْدُ الرَّحْمَنِ بِسِوَاكٍ، فَضَعُفَ النَّبِيُّ صلى الله عليه وسلم عَنْهُ، فَأَخَذْتُهُ فَمَضَغْتُهُ ثُمَّ سَنَنْتُهُ بِهِ.
“The Prophet (ﷺ) died in my house on the day of my turn while he was leaning on my chest closer to my neck, and Allah made my saliva mix with his Saliva.” Aisha رضى الله عنها added, “AbdurRahman came with a Siwak and the Prophet (ﷺ) was too weak to use it so I took it, chewed it and then (gave it to him and he) cleaned his teeth with it.” [Sahih al-Bukhari 3100]
It comes in Al-Mausoo’atil Fiqhiyyah that: “Fuqahaa (scholars of jurisprudence) of 4 Madhhabs (schools of thought) agreed that the best (thing to clean the teeth with) is: the Arak, for the good taste and smell in it, and the bristles in it cleans out (anything) in-between the teeth. And for the Hadith of Abu Khayrah As-‘Sabaahy, he said: I was in the delegation, meaning; the delegation of ‘Abdul-Qais, who went to the Prophet (ﷺ) ((and he order us (to use) Arak and said: brush the teeth with it). And for it (i.e. Arak) being the last thing that Prophet (ﷺ) used to do Siwak (brush his teeth with before passing away).”
From this we know, whoever brushes his teeth with the intention of following Prophet ﷺ, he has already followed the Sunnah of doing Siwak. And if he uses that specific stick (Arak) to do it, he has done Sunnah upon Sunnah. He has achieved two Sunnah. And whoever doesn’t have the stick, he still can follow that one Sunnah of brushing teeth.
And this is only if he has the good intention of following Prophet ﷺ in doing Siwak. BaarakAllah Feek.