1- Is it incumbent upon one who did not pray Fajr to pray four rak'ahs upon praying the Subh prayer, or not, since Fajr is not obligatory? 2- Is it permissible to suffice with ten rak'ahs of the Rawatib (supererogatory) sunnah prayers if one is unable to perform the two before Fajr, or should the ten rak'ahs be abandoned due to not performing the complete set? 3- If one is unable to pray Fajr and Subh in their prescribed times, which of them is better to pray in its time: Fajr or Subh? And what is the reward for one who prays both of them in their prescribed times?

The Fajr prayer (الصُّبح) and the Dawn prayer (الفجر) are two names for one obligatory prayer. As for the Sunnah of Fajr, it consists of two emphasized rak'ahs, the time for which is after the Adhan of Fajr. If one misses them, it is permissible to make them up immediately after the obligatory prayer, or after sunrise. If the time remaining before sunrise is only sufficient for the obligatory prayer, then it is obligatory to perform the obligatory prayer first, and then the Sunnah can be made up after sunrise. Whoever prays both the obligatory prayer and the Sunnah within their prescribed time will attain their reward and فضلهما.