"The Messenger of Allah would fast until we said he would not break his fast, and he would not fast until we said he does not want to fast. And he never fasted any month in full apart from Ramadan, from the time he came to Al-Madinah." (Using translation from Nasāʾī 2346)
كَانَ رَسُولُ اللهِ ﷺ يَصُومُ حَتَّى نَقُولَ لَا يُرِيدُ أَنْ يُفْطِرَ وَيُفْطِرُ حَتَّى نَقُولَ لَا يُرِيدُ أَنْ يَصُومَ وَمَا صَامَ شَهْرًا مُتَتَابِعًا غَيْرَ رَمَضَانَ مُنْذُ قَدِمَ الْمَدِينَةَ