Riyad as-Salihin, Book 9, Hadith 1168 (In-Book) ⓘ
Ibn 'Umar (May Allah be pleased with them) reported: The Prophet said, "Salat during the night should consist of pairs of but if you fear that morning is near, then pray one Rak'ah as Witr."[Al-Bukhari and Muslim].
وعن ابن عمر رضي الله عنهما، أن النبي صلى الله عليه وسلم ، قال: "صلاة الليل مثنى مثنى، فإذا خفت الصبح فأوتر بواحدة" . ((متفق عليه)) .