Wa alaykum salam wa rahmatuLlahi wa barakatuHu,
Scholars discuss a case in which one would find unpaved streets that mudded over due to rainfall. In more agrarian places and times, the streets would be shared by people and animals alike. And when it would rain, the water would turn the dirt streets into mud that may mix with impurities. On this case Ibn ‘Abd al-Salam related in his Qawa’id 2/54 that Imam Shafi’i held two different opinions (ar: qawlayn). This is also related by Imam al-Haramayn in Nihayat al-Matlab 1/46 and others.
These differing opinions ensue from a principle dealing with a case in which the default ruling (ar: asl) goes up against (ar: ta’arud) a strong probability (ar: ghalib). The asl would be that the streets are pure. The ghalib would be that the mud is impure as it most probably came into contact with filth. When the ghalib is based on mere possibility or on a weak cause, then the ruling is with the asl.
The difference between the two is that there is not any khilaf in the case of mere possibility. And in the case of a weak cause, the asl is preferred according to the soundest opinion. Preferring the asl is what Imam Rafi’i inclined too in al-Sharh al-Kabir 1/74. Moreover, Imam Raf’i mentioned textual evidence in support of maintaining the asl over the ghalib. He mentioned that the Prophet Muhammad (upon him be peace) would pray while carrying small children. And the ghalib in small children is that they are often impure while learning to potty-train. But rather than considering them impure, the Prophet (upon him be peace) practiced on the asl.
The As-hab al-Wujuh related the case of muddy streets as qawlayn; and the tarjih would go to that they are considered pure based on the asl. In al-Ashbah wa al-Naza’ir pg. 65, Suyuti mentioned the asl is taken in this case: the case being compared here (ar: nazir i.e. muddy streets) to a modern public restroom.
In his Manthur 1/330, Zarkashi pointed out that if the notion of probability is supported by something perceivable, like the sight of physical impurity, then in such a case the ruling must go with the ghalib i.e. that it is impure. Furthermore, Zarkashi related from Qarafi that preferring the asl over the ghalib is a dispensation (ar: rukhsah); and if one is in a situation in which there is a conflict between the two (i.e. the asl and the ghalib), then it is prudent (ar: wara’) to practice on the ghalib. And if one is considering an asl v. a mere possibility -both being equally possible- then to move away from the asl (i.e. the ruling of purity) is nothing but blameful misgivings (ar: waswas).
If one walks across a clean public restroom’s dry floor and their garment just touches the ground, after which they leave worried about it being impure, that is waswas. The details above have been provided to give some guidelines in case one encounters a less orderly restroom facility.
And Allah knows best.
Answered by Shaykh Yaqub Abdurrahman