Sunan An-Nasa'i
Hadith #1613
It was narrated from Humaid bin 'Abdur-Rahman- that is Ibn 'Awf, that Abu Hurairah said:""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