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.
Sahih Muslim Book 13, Hadith 261
← Previous Hadith This hadith is narrated by 'Abdullah b. Hani b. Akhi Mutarrif with the same chain of transmitters.

Sahih Muslim Book 13, Hadith 260 Next Hadith → 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.

Sahih Muslim Book 13, Hadith 262