Ahmed bin Manay' أحمد بن منيع · The Book on Al-Witr

he asked Aishah about the Witr of the Prophet. She said: "He would perform Witr during all of the night; (either) its beginning, its middle, or its end. So when he died, his Witr ended, during the approachof As-Sahar."

the Prophet said: "Precede the morning with Al-Witr."