Sunan an-Nasa'i, Volume 3, Book 22, Hadith 2186 (DarusSalam)

It was narrated that 'Abdullah bin Shaqiq said: "I said to Aishah: 'Did the Messenger of Allah offer Duha prayer? She said: "No, unless he was returning from a journey, I Did the Messenger of Allah fast an entire month?' She said: 'No, I do not remember him fasting any month in full apart from Ramadan, and he did not break his fast for a whole month, rather he would fast some of (each month) until he passed away."' '

أَخْبَرَنَا إِسْمَاعِيلُ بْنُ مَسْعُودٍ، قَالَ أَنْبَأَنَا خَالِدٌ، - وَهُوَ ابْنُ الْحَارِثِ - عَنْ كَهْمَسٍ، عَنْ عَبْدِ اللَّهِ بْنِ شَقِيقٍ، قَالَ قُلْتُ لِعَائِشَةَ أَكَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي صَلاَةَ الضُّحَى قَالَتْ لاَ إِلاَّ أَنْ يَجِيءَ مِنْ مَغِيبِهِ ‏.‏ قُلْتُ هَلْ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَصُومُ شَهْرًا كُلَّهُ قَالَتْ لاَ مَا عَلِمْتُ صَامَ شَهْرًا كُلَّهُ إِلاَّ رَمَضَانَ وَلاَ أَفْطَرَ حَتَّى يَصُومَ مِنْهُ حَتَّى مَضَى لِسَبِيلِهِ ‏.‏

sunnah.com