What is Salat al-Zahhafah, and is it permissible to pray two rak'ahs after Witr and before Fajr?

The "creeping prayer" (Salat al-Zahhafah) consists of two rak'ahs prayed after Witr while sitting. Scholars have differed regarding their legitimacy. Many have held them to be illegitimate based on the Prophet's (peace and blessings be upon him) saying: "Make the last of your prayer at night Witr." Some have said that these are the two rak'ahs of Fajr. However, others, such as Al-Awza'i and Ahmad, held them to be permissible based on the hadith of 'Aishah (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) "would pray eight rak'ahs, then perform Witr, then pray two rak'ahs while sitting."

Ibn Taymiyyah held that Ahmad permitted them, but they are not obligatory. Al-Nawawi explains that the Prophet's performance of them was to demonstrate permissibility, not for regular observance, as this would contradict the ahadith commanding that Witr be the last prayer of the night. Reconciling the ahadith is possible by interpreting the performance of the two rak'ahs as a demonstration of permissibility.