Sunan an-Nasa'i 2244
سنن النسائي#2244SahihIt was narrated from Abu Hurairah that the Messenger of Allah said:"Whoever fasts one day in the cause of Allah, the Mighty and sublime, Allah will remove his face away from the fire in return for the day (the distance of) seventy autumns
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 ZaiIsnaad Sahih
In-book reference: 22:155