Musnad Ahmad 303:17

Rawh narrated to us, he said: Sa’id narrated to us, from Qatadah, from Mutarrif ibn ‘Abdullah ibn al-Shikhkhir, from his father, that he asked the Prophet, peace and blessings of Allah be upon him, or the Prophet of Allah, peace and blessings of Allah be upon him, was asked about a man who fasts forever. He said: "He has neither fasted nor broken his fast."