It is narrated from Sayyiduna Junadah bin Abi Umayyah al-Azdi (may Allah be pleased with him) that they came to the Messenger of Allah (peace and blessings be upon him) as a group of eight, he (Junadah) himself being the eighth of them. The Messenger of Allah (peace and blessings be upon him) placed food before them on a Friday and said: "Eat." They said: "We are fasting." He asked: "Did you fast yesterday?" They said: "No." He asked: "Will you fast tomorrow?" They said: "No." He said: "Then break your fast."
Hadith Referenceالمعجم الكبير للطبراني / باب الجيم / 2163