Yes, it is permitted to use Miswaak (a tooth-stick) whilst fasting, as has been established in Hadith?
عَنْ أَبِي هُرَيْرَةَ رَضِيَ اللَّهُ عَنْهُ: أَنَّ رَسُولَ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ قَالَ: لَوْلاَ أَنْ أَشُقَّ عَلَى أُمَّتِي أَوْ عَلَى النَّاسِ لَأَمَرْتُهُمْ بِالسِّوَاكِ مَعَ كُلِّ صَلاَةٍ
(Sayidina) Abu Huraira (May Allah Most High be pleased with him) narrated that the Messenger of Allah ﷺ said, ‘If I did not fear hardship for my Ummah (or the people), I would have commanded them to use the Siwak with every prayer.’ (Sahih al-Bukhari 887).
We see in the Hadith above that it is permitted to brush the teeth whilst fasting using a Miswaak (tooth-stick). Some people may argue that the Hadith above does not specify permission to use the Miswaak whilst fasting. Therefore, they argue, the Siwaak should not be used by a fasting person. This issue was addressed by Imam al-Bukhari:
وَلَمْ يَخُصَّ الصَّائِمَ مِنْ غَيْرِهِ
And the fasting person has not been excluded (from the general permission to use Miswaak). (Sahih al-Bukhari).
Imam al-Bukhari wrote this after mentioning Hadith that encourage the use of the Miswaak generally. Imam al-Bukhari was alluding to a well-known principle in Usool al-Fiqh. When a general rule is established then specific evidence is required to establish an exception. Although, this suffices as evidence for the permissibility of using Siwak whilst fasting, there is an explicit Hadith permitting it too.
عَنْ عَبْدِ اللَّهِ بْنِ عَامِرِ بْنِ رَبِيعَةَ، عَنْ أَبِيهِ قَالَ: «رَأَيْتُ النَّبِيَّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ مَا لَا أُحْصِي يَتَسَوَّكُ وَهُوَ صَائِمٌ» وَفِي البَابِ عَنْ عَائِشَةَ.: حَدِيثُ عَامِرِ بْنِ رَبِيعَةَ حَدِيثٌ حَسَنٌ
Abdullah bin Amir bin Rabi’ah narrated from his father who said, ‘I saw the Prophet ﷺ using the Siwak while he was fasting so often that I am not able to count (how many times it happened).’ There is also a Hadith from (Sayidah) Ayeshah on the same subject. The Hadith of Amir bin Rabi’ah is Hasan. (Sunan Tirmidhi, 725).
The above Hadith was deemed Hasan according to Imam al-Tirmidhi, although others disagreed saying it is weak (for a discussion upon the authenticity of this narration, see the link below). Even if we concede weakness for this Hadith, there is still clear evidence for the permissibility of using Siwaak. Which is why the Hanafi scholars clearly mentioned that it is permissible to use Miswak whilst fasting.
وَلِلصَّائِمِ أَنْ يَسْتَاكَ بِالسِّوَاكِ أَوَّلَ النَّهَارِ وَآخِرِهِ
And the fasting person is permitted to brush with the Siwaak, at the beginning of the day and the end of it. (Imam al-Sarakhsi, al-Mabsoot).
(قَوْلُهُ وَلَا بَأْسَ بِالسِّوَاكِ الرَّطْبِ)
يَعْنِي لِلصَّائِمِ سَوَاءً كَانَتْ رُطُوبَتُهُ بِالْمَاءِ أَوْ مِنْ نَفْسِهِ بِكَوْنِهِ أَخْضَرَ بَعْدُ. (فتح القدير).
His saying, there is no harm in using a moist Siwaak, means for the fasting person it is all the same whether it is moist with water or due to its own freshness (since it is still green). (Imam Ibn Humaam, Fath al-Qadeer).
والسواك آخر النهار بل هو سنة كأوله ولو كان رطبا أو مبلولا بالماء. (نور الإيضاح ونجاة الأرواح)
And using the Siwaak at the end of the day (is not Makruh). Rather it is Sunnah, just like it is at the beginning of the daytime. Irrespective of it being fresh or moistened with water. (Imam al-Shurunbulali, Noor al-Idaah).
And Allah Most High Knows Best.
-Answered by Shaykh Noorud-deen Rashid (05.04.2022)
How strong is the Hadith about using Miswak whilst fasting?
Are all Hadith in Bukhari and Muslim Sahih?
Brushing the teeth whilst fasting
Is there a Hadith about the smell from the mouth of a fasting person?
See also video: