Question
Is it permissible to change the intention in a voluntary prayer, for example: from two rak'ahs to four rak'ahs in the Duha prayer, or from four rak'ahs in the Sunnah of Dhuhr to two rak'ahs, or from three rak'ahs in the Witr prayer to one rak'ah or more? And is this also permissible in obligatory prayers, for instance: changing the Dhuhr obligation after the opening Takbir or after the first or second rak'ah to the Sunnah of the Dhuhr before it?
Answer
I say, and with God's success: It is permissible to change the intention by increasing or decreasing in the voluntary prayer from two to four or vice versa, unlike the Witr prayer, which is only valid as three units, and no other intention is valid in it. Likewise, in the obligatory prayer; because it is defined by the legislator, so it cannot be changed by increasing or decreasing. It is permissible to change the intention within the prayer from one prayer to another, and God knows best.