Sunan an-Nasa'i 2255
سنن النسائي#2255SahihIt was narrated that Kab bin 'Asim said:"I heard the Messenger of Allah say; 'It is not righteousness to fast when traveling
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
In-book reference: 22:166