The Book of Qiyam Al-Lail (The Night Prayer) and Voluntary Prayers During the Day
20/26. Chapter:
How to pray at night
Sunan an-Nasai
أَخْبَرَنَا قُتَيْبَةُ، قَالَ حَدَّثَنَا اللَّيْثُ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، عَنِ النَّبِيِّ صلى الله عليه وسلم قَالَ " صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى فَإِذَا خِفْتَ الصُّبْحَ فَأَوْتِرْ بِوَاحِدَةٍ " .
It was narrated from Ibn Umar that: The Prophet (ﷺ) said: "prayers at night are (offered) two by two, then if you fear that dawn will come, pray witr with one."
Reference : Sunan an-Nasa'i 1671In-book reference : Book 20, Hadith 74English translation : Vol. 2, Book 20, Hadith 1672