The Prophet ﷺ used to fast so continuously that people would say, "He fasts, he fasts," and he would refrain from fasting so continuously that people would say, "He has stopped fasting, he has stopped fasting."
حدثنا أبو كامل واسمه مظفر بن مدرك حدثنا حماد بن سلمة عن ثابت
أن النبي ﷺ كان يصوم حتى يقال صام صام ويفطر حتى يقال أفطر أفطر
Its isnad is sahih, it has occurred often, and it is found in Bukhari 4/213 no. 1969 in Fath al-Bari, in the book of fasting, on fasting in Shaban, and in Muslim 2/812 no. 1158 in the book of fasting, on the Prophet's ﷺ fasting, and in Tirmidhi 3/131 no. 768 in the book of fasting, on what has been said about continuous fasting, where he said, hasan sahih, and in Ibn Majah 1/545 no. 1710, similar to Muslim.