(47) باب غَزْوَةِ الْفَتْحِ فِي رَمَضَانَ
Narrated Tawus:
Ibn `Abbas said, "Allah's Messenger (ﷺ) travelled in the month of Ramadan and he fasted till he reached (a place called) 'Usfan, then he asked for a tumbler of water and drank it by the daytime so that the people might see him. He broke his fast till he reached Mecca." Ibn `Abbas used to say, "Allah's Apostle fasted and sometimes did not fast while traveling, so one may fast or may not (on journeys)"
Reference: Sahih al-Bukhari 4279
In-book reference: Book 64, Hadith 313
USC-MSA web (English) reference(deprecated numbering scheme): Vol. 5, Book 59, Hadith 576