Can cleaning agents made from fats and oils of unknown animal origin, which are chemically transformed into soap, be considered pure through chemical transformation (istihalah), by analogy to the purity of a pig or carrion if they are transformed into salt?

If animal fats and oils undergo a chemical transformation into other substances, they become pure and permissible to use, even if their origin was impure. Their ruling then becomes similar to that of salt, into which an impure substance has transformed.

However, if they have not transformed and cleaning products are made from them, and their condition is unknown, one should refer to circumstantial evidence. If their source is a non-Islamic country that does not observe legal slaughter (Dhabihah), it is highly probable that they are impure. Jurists have differed regarding the ruling on using soap made from impure or contaminated substances:

Hanafis and Malikis: They consider soap made from impure or contaminated oil to be pure and permit its use. Shafi'is: They permit benefiting from soap made from impure oil, but they did not explicitly state its purity. Malikis: They differentiated between that which is inherently impure (najis) and that which has become impure (mutanajjis), permitting the use of the latter but not the former, except in the mosque or for human consumption. Hanbalis: They hold that impurity does not become pure through transformation. Therefore, soap made from impure oil remains impure according to them.

Given the widespread prevalence of such cleaning products, the opinion permitting their use is inclined towards alleviating hardship. However, piety dictates avoiding them if their purity is not known.