(4) Prayer
كتاب الصلاة
(36c) Chapter: The Witr - Section 3
(35) باب الوتر - الفصل الثالث
Mishkat al-Masabih 1286 
Thauban reported the Prophet as saying, “This wakefulness is a toil and a burden, so when one of you observes a witr he should pray two rak'as. If he gets up during the night, well and good; otherwise they will serve for him." Tirmidhi transmitted it.
وَعَنْ ثَوْبَانَ عَنِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ قَالَ: «إِنَّ هَذَا السَّهَرَ جُهْدٌ وَثِقَلٌ فَإِذَا أَوْتَرَ أَحَدُكُمْ فَلْيَرْكَعْ رَكْعَتَيْنِ فَإِنْ قَامَ مِنَ اللَّيْلِ وَإِلَّا كَانَتَا لَهُ» . رَوَاهُ الدَّارِمِيُّ
 صَحِيح  (الألباني)حكم :
Reference : Mishkat al-Masabih 1286
In-book reference : Book 4, Hadith 697