Sahih Muslim Book 6, Hadith Number 2472.

Chapter : Permissibility of observing the fast or not observing it in the month of Ramadan for a traveller.

Jabir b. ‘Abdullah (Allah be pleased with both of them) reported that Allah’s Messenger (may peace be upon him) went out to Mecca in Ramadan in the year of Victory, and he and the people fasted till he came to Kura’ al-Ghamim and the people also fasted. He then called for a cup of water which he raised till the people saw it, and then he drank. He was told afterwards that some people had continued to fast, and he said: These people are the disobedient ones; these are the disobedient ones.