Sunan an-Nasa'i 2190
سنن النسائي#2190SahihIt was narrated from Abu Hurairah that the Messenger of Allah used to say:"Do not fast one or two days ahead of the month, unless the one who used to observe a regular fast. In that case let him fast
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 ZaiHasan
In-book reference: 22:101