Abdullah bin Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) set out on a journey in the month of Ramadan and fasted until he reached al-Kadid, and then he broke the fast; and the proof is taken from his last action.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 8173