that the Prophet ﷺ said, "The best ˹voluntary˺ ritual prayer after the farḍ (mandatory) prayer is ˹that which is done˺ in the middle of the night."   

أَنَّ النَّبِيَّ ﷺ قَالَ «أَفْضَلُ الصَّلَاةِ بَعْدَ الْفَرِيضَةِ الصَّلَاةُ فِي جَوْفِ اللَّيْلِ»