One may choose between praying them all together or to separate them. ‘Aishah says: “The Messenger of Allah never prayed more than eleven rak’at, during Ramadan or otherwise. He would pray four rak’at, and don’t ask about how excellent they were or how lengthy they were. Then, he would pray four rak’at, and don’t ask about how excellent they were or how lengthy they were. Then, he would pray three rak’at. I asked: ‘O Messenger of Allah, do you sleep before praying witr?’ he replied: ‘O ‘Aishah, my eyes sleep but my heart does not sleep.”‘ This is recorded by al-Bukhari and Muslim who also record that al-Qasim ibn Muhammad said that he heard ‘Aishah say: “The Messenger of Allah’s prayer during the night would be ten rak’at and then he would make witr with one rak’ah.”
Section : It is preferable to pray eleven or thirteen rak’at for tahajjud.