But if the two have mixed so that neither can be distinguished from the other, whatever reaches a person will consist of both. The fuel, however, is not mixed together where it lies; rather, the ash of each impure substance remains in its own location.

If it is objected:

When the lawful cannot be distinguished from the unlawful—as when a man cannot distinguish his sister from an unrelated woman, or carrion from a lawfully slaughtered animal—he must avoid both. Likewise, when pure water cannot be distinguished from impure water, one view is that he should exercise judgment in choosing water for purification, provided that the impure liquid is not intrinsically impure, as urine is. This is the view of al-Shāfiʿī.

Another view is that he should not exercise judgment but must avoid both, just as he would if one of them were urine. This is the well-known position in Ahmad’s school and the view of a group of Mālik’s followers.

A third view is that he should exercise judgment if the vessels are larger. This is the position of Abū Hanīfah and a group of Ahmad’s followers. They have a well-known disagreement over what counts as large. Here, too, impure substances cannot be distinguished from pure ones, and thus the lawful cannot be distinguished from the unlawful.

The answer is:

This is correct, but the case we are discussing does not fall into this category. When the lawful cannot be distinguished from the unlawful, one avoids both because using both would necessarily entail using what is unlawful, which is impermissible. This is equivalent to the lawful and unlawful being mixed together in such a way that they cannot be distinguished, as when impurity becomes apparent in water. If, on the other hand, one uses either of them without any basis recognized by Islamic law, this would amount to preferring one without grounds for doing so. Both stand on an equal footing with respect to the ruling, so using one is no more justified than using the other. Both must therefore be avoided.