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).

[Al-Bukhari and Muslim].

وعنه قال: كان النبي ﷺ ، يصلي من الليل مثنى مثنى، ويوتر بركعة. ((متفق عليه)) .