Sahih Muslim Book - 6, Hadith - 1751

وَحَدَّثَنِى أَبُو الرَّبِيعِ الزَّهْرَانِىُّ حَدَّثَنَا حَمَّادٌ حَدَّثَنَا أَيُّوبُ وَبُدَيْلٌ عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ عَنْ عَبْدِ اللَّهِ بْنِ عُمَرَ أَنَّ رَجُلاً سَأَلَ النَّبِىَّ -صلى الله عليه وسلم- وَأَنَا بَيْنَهُ وَبَيْنَ السَّائِلِ فَقَالَ يَا رَسُولَ اللَّهِ كَيْفَ صَلاَةُ اللَّيْلِ قَالَ « مَثْنَى مَثْنَى فَإِذَا خَشِيتَ الصُّبْحَ فَصَلِّ رَكْعَةً وَاجْعَلْ آخِرَ صَلاَتِكَ وِتْرًا ». ثُمَّ سَأَلَهُ رَجُلٌ عَلَى رَأْسِ الْحَوْلِ وَأَنَا بِذَلِكَ الْمَكَانِ مِنْ رَسُولِ اللَّهِ -صلى الله عليه وسلم- فَلاَ أَدْرِى هُوَ ذَلِكَ الرَّجُلُ أَوْ رَجُلٌ آخَرُ فَقَالَ لَهُ مِثْلَ ذَلِكَ.

It was narrated from 'Abdullah bin 'Umar that a man asked the Prophet (s.a.w), when I was between him and the one who was asking, saying: "O Messenger of Allah, how are the night prayers?" He said: "Two by two, then when you fear that dawn may come, then pray one Rak'ah, and make the last of your prayer Witr." Then a man asked him, one year later, and I was in the same position with regard to the Messenger of Allah (s.aw), and I do not know whether it was the same man or another man, and he told him something similar.