Compiled by Imam Yahya ibn Sharaf al-Nawawi
وعن ابن عمر رضي الله عنهما، أن النبي صلى الله عليه وسلم ، قال: "صلاة الليل مثنى مثنى، فإذا خفت الصبح فأوتر بواحدة". ((متفق عليه)) .
The Prophet (ﷺ) 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].