حَدَّثَنِي مُحَمَّدُ بْنُ جَعْفَرٍ حَدَّثَنَا شُعْبَةُ عَنْ أَبِي بِشْرٍ عَنْ سَعِيدِ بْنِ جُبَيْرٍ عَنِ ابْنِ عَبَّاسٍ قَالَ كَانَ رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَصُومُ حَتَّى نَقُولَ لَا يُرِيدُ أَنْ يُفْطِرَ وَيُفْطِرُ حَتَّى نَقُولَ لَا يُرِيدُ أَنْ يَصُومَ وَمَا صَامَ شَهْرًا مُتَتَابِعًا غَيْرَ رَمَضَانَ مُنْذُ قَدِمَ الْمَدِينَةَ
مسند امام احمد بن حنبل · Hadith 2151
It was narrated that lbn 'Abbas (RA) said: The Messenger of Allah (PBUH) used to fast until we thought that he did not want to stop fasting, and he would not fast until we thought that he did not want to fast, but he did not fast any month in totality apart from Ramadan from the time he came to Madinah.
Sanad
حَدَّثَنِي مُحَمَّدُ بْنُ جَعْفَرٍ حَدَّثَنَا شُعْبَةُ عَنْ أَبِي بِشْرٍ عَنْ سَعِيدِ بْنِ جُبَيْرٍ عَنِ ابْنِ عَبَّاسٍ