“Whoever among you fears that he will not wake up at the end of the night, let him pray Witr at the beginning of the night, then go to sleep. Whoever hopes that he will wake up at the end of the night, let him pray Witr at the end of the night, for recitation (of the Qur’an) at the end of the night is attended (by the angels), and that is better.” (Using translation from Ibn Mājah 1187)   

قَالَ رَسُولُ اللهِ ﷺ مَنْ خَافَ أَنْ لَا يَسْتَيْقِظَ آخِرَ اللَّيْلِ فَلْيُوتِرْ أَوَّلَهُ ثُمَّ لِيَرْقُدْ وَمَنْ طَمِعَ أَنْ يَسْتَيْقِظَ مِنْ آخِرِ اللَّيْلِ فَلْيُوتِرْ مِنْ آخِرِ اللَّيْلِ فَإِنَّ قِرَاءَةَ آخِرِ اللَّيْلِ مَحْضُورَةٌ وَذَلِكَ أَفْضَلُ  

He who amongst you is afraid that he may not be able to get up at the end of the night should observe Witr (in the first part) and then sleep, and he who is confident of getting up and praying at night (i. e. Tahajjud prayer) should observe it at the end of it, for the recitation at the end of the night is witnessed*, and that is better. *: meaning, "by angels" (Sharh an-Nawawi) (Using translation from Muslim 755b)   

سَمِعْتُ النَّبِيَّ ﷺ يَقُولُ أَيُّكُمْ خَافَ أَنْ لَا يَقُومَ مِنْ آخِرِ اللَّيْلِ فَلْيُوتِرْ ثُمَّ لِيَرْقُدْ وَمَنْ وَثِقَ بِقِيَامِ اللَّيْلِ فَلْيُوتِرْ مِنْ آخِرِهِ فَإِنَّ قِرَاءَةَ آخِرِ اللَّيْلِ مَحْضُورَةٌ وَذَلِكَ أَفْضَلُ  

[Machine] The Prophet ﷺ asked Abu Bakr, "When do you pray the Witr prayer?" Abu Bakr replied, "I pray Witr before I sleep." The Prophet ﷺ then asked Umar, "When do you pray the Witr prayer?" Umar replied, "I sleep and then pray Witr." The Prophet ﷺ said to Abu Bakr, "Have you taken the firm resolution or made the firm intention?" And he said to Umar, "Have you taken strong measures?" (Hadith source reference)  

أَنَّ النَّبِيَّ ﷺ قَالَ لِأَبِي بَكْرٍ ؓ مَتَى تُوتِرُ؟ قَالَ أُوتِرُ قَبْلَ أَنْ أَنَامَ وَقَالَ لِعُمَرَ ؓ مَتَى تُوتِرُ؟ قَالَ أَنَامُ ثُمَّ أُوتِرُ فَقَالَ لِأَبِي بَكْرٍ ؓ أَخَذْتَ بِالْحَزْمِ أَوْ بِالْوَثِيقَةِ وَقَالَ لِعُمَرَ ؓ أَخَذْتَ بِالْقُوَّةِ 4840 وَأَخْبَرَنَا أَبُو عَبْدِ اللهِ الْحَافِظُ وَأَبُو بَكْرِ بْنُ الْحَسَنِ الْقَاضِي قَالَا ثنا أَبُو الْعَبَّاسِ هُوَ الْأَصَمُّ ثنا أَبُو أُمَيَّةَ الطَّرَسُوسِيُّ ثنا يَحْيَى بْنُ إِسْحَاقَ فَذَكَرَهُ بِمَعْنَاهُ إِلَّا أَنَّهُ قَالَ أَخَذَ بِالْحَزْمِ وَلَمْ يَشُكَّ  

[Machine] That the Prophet ﷺ said to Abu Bakr, "When do you pray the Witr (night prayer)?" He said, "I pray the Witr and then sleep." He said, "With determination, I also asked Umar, and he said, 'When do you pray the Witr?' I said, 'I sleep and then wake up during the night and pray the Witr.'" He said, "The action of a strong person, you have done."  

أَنَّ النَّبِيَّ ﷺ قَالَ لِأَبِي بَكْرٍ ؓ مَتَى تُوتِرُ؟ قَالَ أُوتِرُ ثُمَّ أَنَامُ قَالَ بِالْحَزْمِ أَخَذْتَ وَسَأَلَ عُمَرَ فَقَالَ مَتَى تُوتِرُ؟ قَالَ أَنَامُ ثُمَّ أَقُومُ مِنَ اللَّيْلِ فَأُوتِرُ قَالَ فِعْلُ الْقَوِيِّ فَعَلْتَ  

[Machine] My friend, Khalil, advised me to do three things: fasting three days of every month, praying two units of Duha (forenoon prayer), and performing the Witr prayer before going to sleep. Abu Amr Muhammad ibn Abdullah al-Adib informed us, Abu Bakr al-Isma'ili narrated to us, Ja'far ibn Muhammad al-Firyabi narrated to us, Shayban ibn Farrokh narrated to us, and Abdul Warith mentioned it with a similar narration except that he said, "Abu Uthman, meaning al-Nahdi, narrated to me."  

أَوْصَانِي خَلِيلِي ﷺ بِثَلَاثٍ بِصِيَامِ ثَلَاثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ وَرَكْعَتَيِ الضُّحَى وَأَنْ أُوتِرَ قَبْلَ أَنْ أَرْقُدَ 4843 وَأَخْبَرَنَا أَبُو عَمْرٍو مُحَمَّدُ بْنُ عَبْدِ اللهِ الْأَدِيبُ أنبأ أَبُو بَكْرٍ الْإِسْمَاعِيلِيُّ ثنا جَعْفَرُ بْنُ مُحَمَّدٍ الْفِرْيَابِيُّ ثنا شَيْبَانُ بْنُ فَرُّوخَ ثنا عَبْدُ الْوَارِثِ فَذَكَرَهُ بِمِثْلِهِ إِلَّا أَنَّهُ قَالَ حَدَّثَنِي أَبُو عُثْمَانَ يَعْنِي النَّهْدِيَّ