Likewise, those whose rational judgment carries weight agree that the obligation is not, in reality, a particular act, and that Allah has not made obligatory upon a person the very act He knows that person will perform. Only some who are mistaken maintain this, and one group wrongly attributes this view to another. Rather, He has obliged the person to do either this or that. As Ibn Abbās said:
“Every passage in the Quran containing ‘or.......or’ allows a choice, while every passage containing ‘but whoever cannot find’ requires following the prescribed order.”
Allah knows that His servant will perform one particular act, while also knowing that He has not made that act specifically obligatory for him.
People have differed confusedly over this point: Are all three acts obligatory, so that there is no distinction between an obligation specifying an act and an obligation allowing a choice? Or is one unspecified act obligatory, so that what is commanded is ambiguous and unknown to the person commanded? Yet a command must allow the person commanded to know what is required and to carry it out. The view that all three are obligatory is attributed to the Muʿtazilah, while the view that one unspecified act is obligatory is that of the jurists.
The truth of the matter is that the obligation concerns what the three have in common: what is denoted by the expression ‘one of them.’
Thus, what is obligatory is one of the three. This is a known, distinct concept, understood by the person commanded. What this expression denotes is realized in this particular act, in that particular act, and in the third particular act. It is not that one particular yet unspecified act has been made obligatory; rather, one of the particular alternatives has been made obligatory. Compliance is achieved by performing any one of them, even though the command-giver has not specified which.
The contradiction would be to make a particular act obligatory without specifying it. But when the obligation does not concern a particular act, but rather what the alternatives have in common, there is no incompatibility between imposing the obligation and leaving the particular act unspecified.