The Prophet ﷺ never fasted a full month except the month of Ramadan, and he used to fast till one could say, "By Allah, he will never stop fasting," and he would abandon fasting till one would say, "By Allah, he will never fast."  

مَا صَامَ النَّبِيُّ ﷺ شَهْرًا كَامِلاً قَطُّ غَيْرَ رَمَضَانَ وَيَصُومُ حَتَّى يَقُولَ الْقَائِلُ لاَ وَاللَّهِ لاَ يُفْطِرُ وَيُفْطِرُ حَتَّى يَقُولَ الْقَائِلُ لاَ وَاللَّهِ لاَ يَصُومُ  

Messenger of Allah ﷺ used to leave fasting in a certain month till we thought that he would not fast in that month, and he used to fast in another month till we thought he would not stop fasting at all in that month. And if one wanted to see him praying at night, one could see him (in that condition), and if one wanted to see him sleeping at night, one could see him (in that condition) too.  

أَنَّهُ سَمِعَ أَنَسًا ؓ يَقُولُ كَانَ رَسُولُ اللَّهِ ﷺ يُفْطِرُ مِنَ الشَّهْرِ حَتَّى نَظُنَّ أَنْ لاَ يَصُومَ مِنْهُ وَيَصُومُ حَتَّى نَظُنَّ أَنْ لاَ يُفْطِرَ مِنْهُ شَيْئًا وَكَانَ لاَ تَشَاءُ تَرَاهُ مِنَ اللَّيْلِ مُصَلِّيًا إِلاَّ رَأَيْتَهُ وَلاَ نَائِمًا إِلاَّ رَأَيْتَهُ وَقَالَ سُلَيْمَانُ عَنْ حُمَيْدٍ أَنَّهُ سَأَلَ أَنَسًا فِي الصَّوْمِ  

I asked Anas about the fasting of the Prophet. He said "Whenever I liked to see the Prophet ﷺ fasting in any month, I could see that, and whenever I liked to see him not fasting, I could see that too, and if I liked to see him praying in any night, I could see that, and if I liked to see him sleeping, I could see that, too." Anas further said, "I never touched silk or velvet softer than the hand of Messenger of Allah ﷺ and never smelled musk or perfumed smoke more pleasant than the smell of Messenger of Allah ﷺ."  

عَنْ صِيَامِ النَّبِيِّ ﷺ فَقَالَ مَا كُنْتُ أُحِبُّ أَنْ أَرَاهُ مِنَ الشَّهْرِ صَائِمًا إِلاَّ رَأَيْتُهُ وَلاَ مُفْطِرًا إِلاَّ رَأَيْتُهُ وَلاَ مِنَ اللَّيْلِ قَائِمًا إِلاَّ رَأَيْتُهُ وَلاَ نَائِمًا إِلاَّ رَأَيْتُهُ وَلاَ مَسِسْتُ خَزَّةً وَلاَ حَرِيرَةً أَلْيَنَ مِنْ كَفِّ رَسُولِ اللَّهِ ﷺ وَلاَ شَمِمْتُ مِسْكَةً وَلاَ عَبِيرَةً أَطْيَبَ رَائِحَةً مِنْ رَائِحَةِ رَسُولِ اللَّهِ ﷺ