Answered by Ustadh Sufyan Qufi
I experience, and I think many do, that sometimes people in their back passage get some type of yellow/brown stain maybe due to sweat or other circumstances. What if it was on someones underwear as usually people may have it on there as well, does it also take the ruling of 5cm of filth?
In the name of Allah, Most Compassionate, Most Merciful,
If one is sure that the yellow stain is of fecal origin, then praying while wearing those underwear won’t be valid unless the stain is not larger than a circle of five centimeters in diameter. [Shurunbulali, Nur al-Idah]
If one doubts the origin of this stain, thinking that it may be sweat, then praying in that underwear is valid even if the stain is larger than a circle of five centimeters in diameter. [Ibid]
The reason for this ruling is that incidental doubts regarding the impurity of an item won’t lift its purity as long as you are sure that the item was pure before those doubts.
This legal principle is an application of another legal principle: “Certainty is not lifted by a doubt.” [Majalla]
Which is, in turn, based on the following verse of the Quran: “Most of them follow nothing but conjectures. Surely, conjectures are of no avail in the matter of truth at all.” [Quran, 10:36] [Du‘ass, al-Qawa‘id al-Fiqhiyya]
And Allah knows best.
[Ustadh] Sufyan Qufi
Checked and Approved by Shaykh Faraz Rabbani
Ustadh Sufyan Qufi is an advanced seeker of knowledge, originally from Algeria, who grew up in France. He began searching far and wide for answers to the fundamental questions of life and was disappointed at the answers he found. Then he connected with various traditional teachers and gradually connected with SeekersGuidance. He embarked on his journey of learning through the various teachers at SeekersGuidance, including his mentor Shaykh Faraz Rabbani. He studied numerous texts in Islamic Law, Theology, Hadith, and other areas with Shaykh Faraz Rabbani and other teachers, including Shaykh Abdurrahman al-Sha‘ar, Shaykh Ali Hani, and others. He is an active instructor at SeekersGuidance and answers questions through the SeekersGuidance Answers Service.