(4) Prayer
كتاب الصلاة
(36a) Chapter: The Witr - Section 1
(35) باب الوتر - الفصل الأول
Mishkat al-Masabih 1255 
He reported God’s Messenger as saying, “The witr* is a rak'a at the end of the night.” * Literally ‘single’, or ‘odd’, used of an odd number of rak'as prayed at some time during the night. Muslim transmitted it.
وَعَنِ ابْنِ عُمَرَ قَالَ: قَالَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ: «الْوَتْرُ رَكْعَةٌ مِنْ آخر اللَّيْل» . رَوَاهُ مُسلم
 صَحِيح  (الألباني)حكم :
Reference : Mishkat al-Masabih 1255
In-book reference : Book 4, Hadith 670