Ibn Naṣr said: “The people of knowledge are in agreement that the time between the ‘ishā` prayer and the beginning of fajr is the time for witr. It was narrated from the Prophet (May Allāh praise him and Peace be upon him) that he said to pray witr before fajr begins. [Mukhtaṣar Qiyām Al-Layl, p. 119]

It was also narrated from Jābir (may Allāh be pleased with him) that Allāh’s Messenger (May Allāh praise him and Peace be upon him) said: If somebody fears that he will not get up in the last part of the night, he is to pray witr in the first part of the night. If he expects to get up in the last part of the night, he is to pray witr in the last part of the night. That is because prayer in the last part of the night is witnessed. [Reported by Muslim (755)]