The Messenger of Allah ﷺ said, "He who fasts perpetually has not fasted at all."
حدثنا علي بن محمد حدثنا وكيع عن مسعر وسفيان عن حبيب بن أبي ثابت عن أبي العباس المكي
قال رسول الله ﷺ لا صام من صام الأبد
No references are available.
Sourced by Bukhari, Fasting, chapter on the fasting of Dawud , hadith no. 1979, and Muslim, Fasting, chapter on the prohibition of fasting continuously for one who is harmed by it, etc., hadith no. 1159, from the hadith of Habib, transmitted through the same chain, at length.