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.'
It was narrated from Abu Bishr Ja'far bin Abi Wahshiyyah that: 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.