Riyad as-SalihinChapter 8Hadith 490
Full Sharh — Riyad as-Salihin 490
وعنه قال: كان النبي صلى الله عليه وسلم ، يصلي من الليل مثنى مثنى، ويوتر بركعة. ((متفق عليه)) .
English Translation
Ibn 'Umar (May Allah be pleased with them) reported:: The Prophet (ﷺ) performed the night prayer in pairs (i.e., Rak'ah) and made it odd number by observing one Rak'ah (as Witr)..
Source
Riyad as-Salihin(رياض الصالحين)
The Book of Virtues
Hadith Number
490