Sayyidah Asma bint Yazid (may Allah be pleased with her) said: One day we were with the Prophet (peace and blessings be upon him) when a drink was brought. He (peace and blessings be upon him) drank, then gave it to the people and they drank. Then the vessel passed by a man, and he said: I am fasting. Some of the people said: He never breaks his fast; he fasts every day. So the Prophet (peace and blessings be upon him) said: "Whoever fasts perpetually has neither fasted nor broken his fast."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20823