Sunan an Nasai
1674
Sahih+2

It was narrated that Abdullah bin Umar said:"A man stood up and said: 'O Messenger of Allah (ﷺ), how are the prayers at night to be done?' The Messenger of Allah (ﷺ) said: 'Prayers at night are (offered) two by two, then if you fear that dawn will come, pray witr with one

SahihAbu Ghuddah
SahihAl-Albani