Fatwa ID: 04035
Answered by: Alimah Nasima Umm Hamza
I just found out the beard brush I've been using since 2016 is made out of boar bristles.
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
The condition of a valid salah is to have the purity of the body, clothes, and place of prayer.
Not considering wudhu, the body and clothing can be considered to be impure when they come into contact with an impure substance.
The whole pig, as well as the hair of the pig, is impure. Therefore, brushes made with boar bristles will not be permissible to use.
If the brush is dry and the hair is dry, then no impurity will pass over, and hence the salah will be valid.
However, if the brush is wet or if the hair is wet and the hair is combed then the impurity would be passed over. This would require the hair to be washed to remove the impurity. And the salah would be required to be repeated.
In your case, because you have used this beard brush since 2016, it would be difficult for you to calculate the number of times the brush was used wet. There is a principle which states that in when a matter becomes difficult, it should be made flexible.
الأَمرُ إِذْ ضَاقَ اِتَّسَعَ
“A matter when it is restricted, it will become vast.”
Based on this, for your past prayers, we can take the opinion of Imam Muhammad of the Hanafi School, who permitted the use of pig products out of necessity, and consider that your prayers were all valid when you used the beard brush. You will not have to make any prayers up.
It is advised that you dispose of this brush and be careful to not use products derived from pigs in the future.
Only Allah knows best
Written by Alimah Nasima Umm Hamza
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
 Ibn Abideen, Raddul Muhtaar, Volume 1, Pages 204 and 206
 Ibn Abideen, Raddul Muhtaar, Volume 1, Page 206