Maliks Muwatta Book 18, Hadith Number 21.

Section : Fasting while Travelling.

Yahya related to me from Malik from Ibn Shihab from Ubaydullah ibn Abdullah ibn Utba ibn Masud from Abdullah ibn Abbas that the Messenger of Allah, may Allah bless him and grant him peace, left for Makka in Ramadan during the year of the conquest, and fasted until he reached al-Kadid. He then broke the fast, and so everyone else did so as well. What people used to do was act according to whatever the Messenger of Allah, may Allah bless him and grant him peace, had done most recently.