Sunan an-Nasa'i 1677
سنن النسائي#1677SahihIt was narrated that Abu Hurairah said:"My dearest friend advised me (to do) three things: 'To sleep after praying Witr, to fast three days each month, and to pray two rak'ahs of Fajr
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih - Agreed Upon
In-book reference: 20:80