"The Messenger of Allah ﷺ said: 'The best fasting after the month of Ramadan is the month of Allah, Al-Muharram, and the best prayer is prayer at night.'"  

قَالَ رَسُولُ اللَّهِ ﷺ أَفْضَلُ الصِّيَامِ بَعْدَ شَهْرِ رَمَضَانَ شَهْرُ اللَّهِ الْمُحَرَّمُ وَأَفْضَلُ الصَّلاَةِ بَعْدَ الْفَرِيضَةِ صَلاَةُ اللَّيْلِ  

He heard Humaid bin 'Abdur-Rahman say: "The Messenger of Allah ﷺ said: 'The best prayer after the obligatory (fard) prayers is prayer at night and the best fasting after the month of Ramadan is Al-Muharram.'" Shu'bah bin Al-Hajjaj narrated it in Mursal form.  

قَالَ رَسُولُ اللَّهِ ﷺ أَفْضَلُ الصَّلاَةِ بَعْدَ الْفَرِيضَةِ قِيَامُ اللَّيْلِ وَأَفْضَلُ الصِّيَامِ بَعْدَ رَمَضَانَ الْمُحَرَّمُ أَرْسَلَهُ شُعْبَةُ بْنُ الْحَجَّاجِ