Sunan Abi Dawud 2429
سنن أبي داود#2429SahihNarrated Abu Hurairah:The Messenger of Allah (ﷺ) as saying: The most excellent fast after Ramadan is Allah's month al-Muharram, and the most excellent prayer after the prescribed prayer is the prayer during night
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Muslim (1163)
In-book reference: 14:117