What is the classification and ruling regarding doubtful matters (shubuhat)?
Chapter on Selling the Musarrah (Animal with milk retained in udder)
Al-Mughni
Book of Sales
Primary text
Doubtful matters are categorized into three types. The first type originates from a basis of prohibition (asl al-hadhr). For instance, meat slaughtered in a town containing Zoroastrians and idolaters who slaughter, where purchasing it is impermissible even if it is possible the slaughterer was a Muslim, because the default ruling is prohibition and this is only removed by certainty or a strong presumption. This is evidenced by the Hadith of Adi ibn Hatim regarding sending a dog whose quarry was mixed with others not properly named over, where the Prophet commanded not to eat it because the killer could not be determined. If this situation occurs in a Muslim land, the presumption favors permissibility because Muslims do not allow the apparent sale of what is forbidden.
Supporting text
The second type originates from a basis of permissibility (asl al-ibaha). An example is water found to be changed in condition where it is unknown whether the change was caused by impurity or something else; in this case, the water remains pure in ruling because the default is purity, which is not abandoned except by certainty or strong presumption, neither of which is present. The basis for this is the Hadith of Abdullah ibn Zayd regarding one who suspects passing gas during prayer: he should not leave until he hears a sound or smells an odor. The third type is that where the origin cannot be ascertained, such as in the case of mixed wealth mentioned previously, which is the primary instance of shubha that should be avoided.