(20) باب صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى وَالْوِتْرُ رَكْعَةٌ مِنْ آخِرِ اللَّيْلِ
Ibn Umar reported Allah's Messenger (ﷺ) as saying:
Witr is a rak'ah at the end of the night prayer. (DE)
Reference (DE): Sahih Muslim 752 b (DE)
In-book reference (DE): Book 6, Hadith 187 (DE)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1642 (DE)