Sunan an-Nasa'i 2174
سنن النسائي#2174SahihIt was narrated that Ibn 'Abbas said:"The messenger of Allah said: 'Do not fast one or two days ahead of the month, unless that happens to be a day that one of you habitually fasts."' Abu 'Abdur-Rahman (An-Nasai) said: This is a mistake
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahHasan Sahih
Al-AlbaniHasan Sahih
Zubair Ali ZaiSahih
In-book reference: 22:85