If the owner says, “Your oil increased in value only because it was mixed with my sawiq; therefore, you and I are partners in this increase,” the answer is that, if the owner demands this, his request must be granted—contrary to what the apparent wording of the author suggests. Were we not to rule this way, anyone whose oil was unsaleable could usurp sawiq, mix it with the oil, and thereby increase its value. This is the correct view, because the increase resulted from combining the oil with the sawiq. But if the value of the sawiq—the usurped property—decreases as a result of mixing it with the oil, then the usurper is liable for that decrease.

In summary, the governing principle is that every decrease in the usurped property resulting from an act of the usurper, or otherwise, is guaranteed by the usurper.

The author—may Allah have mercy on him—did not mention the second category, namely, where the property is mixed with something from which it can be distinguished. If it is mixed with something distinguishable, the usurper must separate it, even if this causes him to lose a great deal of wealth. Thus, if he usurps wheat and mixes it with barley, the wheat can be distinguished from the barley. In that case, we say to the usurper: “Separate the wheat from the barley, even if it takes a long time,” because the very property that was usurped still exists, and it must therefore be returned to its owner. If he says, “This harms me,” the answer is: “You are the one who brought this upon yourself. Why did you usurp it in the first place? And why did you mix it afterward?” The Prophet ﷺ said: “No wrongdoer has any right by virtue of his planting.” (1) Therefore, he is required to separate it, even if it costs him many times its value.