" صَلاَةُ اللَّيْلِ مَثْنَى مَثْنَى فَإِذَا أَرَدْتَ أَنْ تَنْصَرِفَ فَارْكَعْ بِوَاحِدَةٍ تُوتِرُ لَكَ مَا قَدْ صَلَّيْتَ "
It was narrated from 'Abdullah bin 'Umar that: The Messenger of Allah (ﷺ) said: "Prayer at night is two by two, then when you want to finish, pray one rak'h which will make the total number that you prayed odd."