Ibn ʿUmar said, "While the Prophet ﷺ was on the pulpit, a man asked him how to offer the night prayers. He replied, 'Pray two rakʿat at a time and then two and then two and so on, and if you are afraid of the dawn (the approach of the time of the Fajr prayer) pray one rakʿa and that will be the witr for all the rakʿat which you have offered." Ibn ʿUmar said, "The last rakʿat of the night prayer should be odd, for the Prophet ﷺ ordered it to be so.  

سَأَلَ رَجُلٌ النَّبِيَّ ﷺ وَهْوَ عَلَى الْمِنْبَرِ مَا تَرَى فِي صَلاَةِ اللَّيْلِ قَالَ مَثْنَى مَثْنَى فَإِذَا خَشِيَ الصُّبْحَ صَلَّى وَاحِدَةً فَأَوْتَرَتْ لَهُ مَا صَلَّى وَإِنَّهُ كَانَ يَقُولُ اجْعَلُوا آخِرَ صَلاَتِكُمْ وِتْرًا فَإِنَّ النَّبِيَّ ﷺ أَمَرَ بِهِ  

A man came to the Prophet ﷺ while he was delivering the sermon and asked him how to offer the night prayers. The Prophet ﷺ replied, 'Pray two rakʿat at a time and then two and then two and so on and if you are afraid of dawn (the approach of the time of the Fajr prayer) pray one rakʿa and that will be the witr for all the rakʿat which you have prayed." Narrated 'Ubaidullah bin ʿAbdullah bin ʿUmar: A man called the Prophet ﷺ while he was in the mosque.  

أَنَّ رَجُلاً جَاءَ إِلَى النَّبِيِّ ﷺ وَهْوَ يَخْطُبُ فَقَالَ كَيْفَ صَلاَةُ اللَّيْلِ فَقَالَ مَثْنَى مَثْنَى فَإِذَا خَشِيتَ الصُّبْحَ فَأَوْتِرْ بِوَاحِدَةٍ تُوتِرُ لَكَ مَا قَدْ صَلَّيْتَ قَالَ الْوَلِيدُ بْنُ كَثِيرٍ حَدَّثَنِي عُبَيْدُ اللَّهِ بْنُ عَبْدِ اللَّهِ أَنَّ ابْنَ عُمَرَ حَدَّثَهُمْ أَنَّ رَجُلاً نَادَى النَّبِيَّ ﷺ وَهُوَ فِي الْمَسْجِدِ  

While Messenger of Allah ﷺ was sitting in the mosque (with some people) three men came, two of them came in front of Messenger of Allah ﷺ and the third one went away, and then one of them found a place in the circle and sat there while the second man sat behind the gathering, and the third one went away. When Messenger of Allah ﷺ finished his preaching, he said, "Shall I tell you about these three persons? One of them betook himself to Allah and so Allah accepted him and accommodated him; the second felt shy before Allah so Allah did the same for him and sheltered him in His Mercy (and did not punish him), while the third turned his face from Allah, and went away, so Allah turned His face from him likewise.  

بَيْنَمَا رَسُولُ اللَّهِ ﷺ فِي الْمَسْجِدِ فَأَقْبَلَ ثَلاَثَةُ نَفَرٍ فَأَقْبَلَ اثْنَانِ إِلَى رَسُولِ اللَّهِ ﷺ وَذَهَبَ وَاحِدٌ فَأَمَّا أَحَدُهُمَا فَرَأَى فُرْجَةً فَجَلَسَ وَأَمَّا الآخَرُ فَجَلَسَ خَلْفَهُمْ فَلَمَّا فَرَغَ رَسُولُ اللَّهِ ﷺ قَالَ أَلاَ أُخْبِرُكُمْ عَنِ الثَّلاَثَةِ أَمَّا أَحَدُهُمْ فَأَوَى إِلَى اللَّهِ فَآوَاهُ اللَّهُ وَأَمَّا الآخَرُ فَاسْتَحْيَا فَاسْتَحْيَا اللَّهُ مِنْهُ وَأَمَّا الآخَرُ فَأَعْرَضَ فَأَعْرَضَ اللَّهُ عَنْهُ