Abu Haraira (Allaah be pleased with him) reported Allaah's Messenger (sallAllaahu alayhi wa sallam) as saying: The most excellent fast after Ramadan is God's month. al-Muharram, and the most excellent prayer after what is prescribed is prayer during the night.
Abu Huraira (Allaah be pleased with him) reported that he (the Messenger of Allaah) was asked as to which prayer was most excellent after the prescribed prayer, and which fast was most excellent after the month of Ramadan. He said: 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.
A hadith like this has been reported from the Prophet of Allaah (sallAllaahu alayhi wa sallam) by 'Abd al-Malik with the same chain of transmitters in connection with fast.