[Machine] He used to pray the last night prayer in the mosque of the Messenger of Allah ﷺ , then he would perform Witr prayer with one unit that he would not exceed. It is said to him, "Do you perform Witr with one unit that you do not exceed, O Abu Ishaq?" He would say, "Yes, indeed, for I heard the Messenger of Allah ﷺ saying, 'The one who does not sleep until he performs Witr is determined.'"  

أَنَّهُ كَانَ يُصَلِّي الْعِشَاءَ الْآخِرَةَ فِي مَسْجِدِ رَسُولِ اللهِ ﷺ ثُمَّ يُوتِرُ بِوَاحِدَةٍ لَا يَزِيدُ عَلَيْهَا قَالَ فَيُقَالُ لَهُ أَتُوتِرُ بِوَاحِدَةٍ لَا تَزِيدُ عَلَيْهَا يَا أَبَا إِسْحَاقَ؟ فَيَقُولُ نَعَمْ إِنِّي سَمِعْتُ رَسُولَ اللهِ ﷺ يَقُولُ الَّذِي لَا يَنَامُ حَتَّى يُوتِرَ حَازِمٌ