Answered by Sidi Suheil Laher
We can find in alot of places here on the fatwa session where you describe impurity in the sice of a dirham to sometimes be different/excused. But I read this on the islamonline.net fatwa session: “There is no authentic evidence that distinguishes between a small or big impurity as far as removing the najasah is concerned.” So is there any evidence for the dirham comparison ?
wa`alaykum as-salam wa-rahmatullah
It is true that there is a very weak hadith that states “Salah is to be repeated from blood the size of a dirham.” However, this narration is not the basis for the Hanafi position, as `Allamah al-`Ayni has stated in his commentary on al-Bukhari.
The primary evidence for the Hanafi position is another hadith:
“When one of you goes to relieve himself, he should clean himself with three stones, for that is sufficient for him.” [Abu Dawud, Nasa’i, Daraqutni]
This hadith establishes that it is not necessary to wash the private part after defacating, and that wiping it with a clean, dry substance (such as stones) is sufficient. It is obvious that this only lessens and dries the impurity of stools; it does not remove them as washing would do. Yet, the hadith implies that someone who performs wudu’, after having performed istinja’ with stones, can pray with this small amount of impurity still remaining on his body, and his salah will be valid. The size of the private part is approximately the size of a dirham. Ibrahim al-Nakha`i, one of the Tabi`in, said, “They [i.e. the scholars] considered it distasteful to mention the anus in their lessons, so they substituted it with ‘dirham’.”
A small amount of impurity (on parts of the body other than the private parts) is often very difficult to avoid without being excessively finicky. In Mukhtasar Minhaj al-Qasidin (Imam Ibn Qudamah al-Hanbali’s abridgement of Imam al-Ghazzali’s Ihya’), it is stated that, “the former generations [salaf] … used to spend their time in purification of the heart, and were [somewhat] lenient in exterior matters.”
The istinja’ hadith mentioned earlier is thus used, by the Hanafis, as a convenient boundary between “little” and “much.”
[References: I`la al-Sunan, `Umdat al-Qari]
And Allah knows best.
-sl