My friend (i.e. the Prophet) instructed me to observe three practices that I do not leave while traveling nor while resident, to pray two rakʿahs in the forenoon, to fast three days every month and not to sleep but after observing the witr.  

أَوْصَانِي خَلِيلِي ﷺ بِثَلاَثٍ لاَ أَدَعُهُنَّ فِي سَفَرٍ وَلاَ حَضَرٍ رَكْعَتَىِ الضُّحَى وَصَوْمِ ثَلاَثَةِ أَيَّامٍ مِنَ الشَّهْرِ وَأَنْ لاَ أَنَامَ إِلاَّ عَلَى وِتْرٍ  

My friend (i.e. the Prophet) instructed me to observe three practices which I never leave: he instructed me to fast three days every month, and not to sleep but after observing the witr, and to observe supererogatory prayer in the forenoon while traveling and while resident.  

أَوْصَانِي خَلِيلِي ﷺ بِثَلاَثٍ لاَ أَدَعُهُنَّ لِشَىْءٍ أَوْصَانِي بِصِيَامِ ثَلاَثَةِ أَيَّامٍ مِنْ كُلِّ شَهْرٍ وَلاَ أَنَامُ إِلاَّ عَلَى وِتْرٍ وَبِسُبْحَةِ الضُّحَى فِي الْحَضَرِ وَالسَّفَرِ  

The Prophet ﷺ asked AbuBakr: When do you observe the witr? He replied: I observe the witr prayer in the early hours of the night. The Prophet ﷺ asked Umar: When do you observe the witr? He replied: At the end of the night. He then said to AbuBakr: This has followed it with care; and he said to Umar: He has followed it with strength.  

أَنَّ النَّبِيَّ ﷺ قَالَ لأَبِي بَكْرٍ مَتَى تُوتِرُ قَالَ أُوتِرُ مِنْ أَوَّلِ اللَّيْلِ وَقَالَ لِعُمَرَ مَتَى تُوتِرُ قَالَ آخِرَ اللَّيْلِ فَقَالَ لأَبِي بَكْرٍ أَخَذَ هَذَا بِالْحَزْمِ وَقَالَ لِعُمَرَ أَخَذَ هَذَا بِالْقُوَّةِ