A manasked Ibn 'Umar:
"How should I perform Witr?" He said: "PrayWitr with one Rak'ah." He said: "I am afraid that the peoplewill saythat I am cutting the prayer short." He said: "TheSunnah of Allah andHis Messenger." Meaning "This is the Sunnahof Allah and HisMessenger." (ID)
English reference (ID): Vol. 1, Book 5, Hadith 1176 (ID)
Arabic reference (ID): Book 5, Hadith 1232 (ID)