Nor is it required, along with intending the noon prayer, to intend that it is being made up, because performing it after its prescribed time suffices in place of intending that it is a make-up prayer.
His statement, “a voluntary prayer,” means that, whether it is an unrestricted voluntary prayer or a specified voluntary prayer, one need not intend it as voluntary. In the case of a specified voluntary prayer, however, specifying it is sufficient.
For example, if one wishes to perform the Witr prayer, it is not necessary for him to intend that it is voluntary. Likewise, if he wishes to perform the regular Sunnah prayer associated with the noon prayer, for example, it is not necessary for him to intend it as voluntary, because specifying it suffices in place of intending it to be voluntary. So long as he has intended it to be the regular Sunnah prayer of the noon prayer, it is voluntary; and so long as he has intended Witr, Witr is voluntary.
Likewise, with an unrestricted voluntary prayer, it is not necessary to intend it as voluntary. For example, if one rises to pray at night, he does not need to intend that it is voluntary, because anything other than the five daily prayers is voluntary.
His statement, “repeating it,” means that, when repeating a prayer, it is not necessary to intend that it is a repetition.
Repeating a prayer means performing it a second time within its prescribed time, whether the first prayer was invalid or not.
For example, if someone performs the noon prayer and then remembers that he was in a state of ritual impurity, he must repeat it, but he is not required to intend that it is a repetition. Similarly, if he performs the noon prayer in one mosque, then comes to another mosque and the call for the prayer is made, it is legislated for him to repeat it. Yet he is not required to intend that it is a repetition, because he has already performed the first prayer and regards this second one as voluntary; therefore, he need not intend it as a repeated prayer.
His statement, “and he forms the intention along with the opening takbir”: here the author mentions the proper time for the intention. The preferable view is that it should coincide with the opening takbir, or precede it by a short interval;