Sunan Ibn Majah
1320
Sahih+3

It was narrated that Ibn ‘Umar said:“The Prophet (ﷺ) was asked about the night prayer. He said: ‘Pray two by two, and if you fear that dawn is coming, then perform Witr with one Rak’ah.’”

SahihAl-Albani
SahihMuhammad Fouad Abd al-Baqi