That the Messenger of Allah used to fast continually and it ws said that he would not break his fast, and he used not to fast and it was said that he would not fast. (Using translation from Nasāʾī 2359)
أَنَّ رَسُولَ اللهِ ﷺ «كَانَ يَسْرُدُ الصَّوْمَ» فَيُقَالُ لَا يُفْطِرُ وَيُفْطِرُ فَيُقَالُ لَا يَصُومُ