(20) باب صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى وَالْوِتْرُ رَكْعَةٌ مِنْ آخِرِ اللَّيْلِ
Salim reported on the authority of his father that a person asked the Messenger of Allah (ﷺ) about the night prayer. He said:
It consists of pairs of rak'ahs, but if one fears morning is near, he should make it an odd number by praying one rak'ah. (ID)
Reference (ID): Sahih Muslim 749 b (ID)
In-book reference (ID): Book 6, Hadith 178 (ID)
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1633 (ID)