[Machine] Abdullah ibn Umar used to perform the "witr" prayer at the beginning of the night. When he got up to pray, he would cancel his "witr" prayer and then pray again. He would then perform another "witr" prayer at the end of the night. Omar used to perform his "witr" prayer at the end of the night and he was better than both Abdullah and myself. Abu Bakr used to perform the "witr" prayer at the beginning of the night and then intercede with another prayer at the end of the night, intending by that to pray in pairs (two units at a time) and not cancel his "witr" prayer.  

كَانَ عَبْدُ اللهِ بْنُ عُمَرَ يُوتِرُ أَوَّلَ اللَّيْلِ فَإِذَا قَامَ نَقَضَ وِتْرَهُ ثُمَّ صَلَّى ثُمَّ أَوْتَرَ آخِرَ صَلَاتِهِ أَوَاخِرَ اللَّيْلِ وَكَانَ عُمَرُ يُوتِرُ آخِرَ اللَّيْلِ وَكَانَ خَيْرًا مِنِّي وَمِنْهُمَا أَبُو بَكْرٍ يُوتِرُ أَوَّلَ اللَّيْلِ وَيَشْفَعُ آخِرَهُ يُرِيدُ بِذَلِكَ يُصَلِّي مَثْنَى مَثْنَى وَلَا يَنْقُضُ وِتْرَهُ