possible? Let us look into the matter. Switching from one specified prayer to another specified prayer, or from an unspecified voluntary prayer to a specified one, is invalid.

Take the case of the unspecified prayer. A person rises to pray an unrestricted voluntary prayer, and in the middle of it he remembers that he has not yet offered the regular sunnah before Fajr, so he decides to convert his intention to that sunnah. We say: it does not count as the Fajr sunnah, because he has moved from something unspecified to something specified, and a specified prayer must be intended from the very beginning—the Fajr sunnah extends from the opening takbīr to the closing salām.

Now consider moving from one specified prayer to another specified prayer. A man starts the ʿAsr prayer, and while praying he recalls that he did not perform Zuhr, or that he prayed it without ablution, so he says: “I now intend this for Zuhr.” Does it count for Zuhr or not? It does not, for he has switched from one specified act to another. Nor is the ʿAsr he began still valid, because he cut it off by switching to Zuhr. Thus the prayer is valid neither as ʿAsr nor as Zuhr: not as ʿAsr, because he interrupted it, and not as Zuhr, because he did not commence it as Zuhr. The Zuhr prayer, like any other, runs from the opening takbīr to the salām.

By contrast, changing from a specified prayer to an unspecified one is permissible. Suppose someone begins an obligatory prayer but, after starting, remembers an appointment he absolutely cannot delay; he then converts his intention to a voluntary prayer. This is valid provided two conditions are met: (1) there is still ample time left for the obligatory prayer, and (2) he will not miss the congregational prayer. For example, if he is actually praying with a congregation, he may not convert it to an unrestricted voluntary prayer, because that would entail abandoning the congregational duty. Likewise, if the time is too tight, he may not turn it into a voluntary prayer, because the obligatory prayer