Prayer offered in the middle of the night and the most excellent fast after (fasting) in the month of Ramadan is the fast in God's month al-Muharram.  

عَنْ أَبِي هُرَيْرَةَ ؓ يَرْفَعُهُ قَالَ سُئِلَ أَىُّ الصَّلاَةِ أَفْضَلُ بَعْدَ الْمَكْتُوبَةِ وَأَىُّ الصِّيَامِ أَفْضَلُ بَعْدَ شَهْرِ رَمَضَانَ فَقَالَ أَفْضَلُ الصَّلاَةِ بَعْدَ الصَّلاَةِ الْمَكْتُوبَةِ الصَّلاَةُ فِي جَوْفِ اللَّيْلِ وَأَفْضَلُ الصِّيَامِ بَعْدَ شَهْرِ رَمَضَانَ صِيَامُ شَهْرِ اللَّهِ الْمُحَرَّمِ  

[Machine] On the authority of Abu Hurairah, he said: It was narrated to the Prophet ﷺ that he was asked, "Which prayer is best after the obligatory prayers?" And, "Which fasting is best after the month of Ramadan?" He replied, "The best prayer after the obligatory prayers is the prayer in the middle of the night. And the best fasting after the month of Ramadan is the fasting in the month of Allah, Muharram."  

عَنْ أَبِي هُرَيْرَةَ يَرْفَعْهُ إِلَى النَّبِيِّ ﷺ أَنَّهُ سُئِلَ أَيُّ الصَّلَاةِ أَفْضَلُ بَعْدَ الْمَكْتُوبَةِ؟ وَأَيُّ الصِّيَامِ أَفْضَلُ بَعْدَ شَهْرِ رَمَضَانَ؟ فَقَالَ «أَفْضَلُ الصَّلَاةِ بَعْدَ الْمَكْتُوبَةِ الصَّلَاةُ فِي جَوْفِ اللَّيْلِ وَأَفْضَلُ الصِّيَامِ بَعْدَ شَهْرِ رَمَضَانَ شَهْرُ اللَّهِ الْمُحَرَّمُ»