Sahih Muslim , Hadith 1157

Ibn Abbas (Allah be pleased with both of them) reported: The Messenger of Allah did not fast throughout any month except during ramadan. And when he observed fast (he fasted so continuously) that one would say that he would not break (them) and when he Abandoned, he abandoned (so continuously) that one would say: By Allah, perhaps he would never fast.

حَدَّثَنَا أَبُو الرَّبِيعِ الزَّهْرَانِيُّ، حَدَّثَنَا أَبُو عَوَانَةَ، عَنْ أَبِي بِشْرٍ، عَنْ سَعِيدِ بْنِ جُبَيْرٍ، عَنِ ابْنِ عَبَّاسٍ، - رضى الله عنهما - قَالَ مَا صَامَ رَسُولُ اللَّهِ صلى الله عليه وسلم شَهْرًا كَامِلاً قَطُّ غَيْرَ رَمَضَانَ ‏.‏ وَكَانَ يَصُومُ إِذَا صَامَ حَتَّى يَقُولَ الْقَائِلُ لاَ وَاللَّهِ لاَ يُفْطِرُ ‏.‏ وَيُفْطِرُ إِذَا أَفْطَرَ حَتَّى يَقُولَ الْقَائِلُ لاَ وَاللَّهِ لاَ يَصُومُ ‏.‏

sunnah.com

This hadith has been narrated on the authority of Abu Bishr with the same chain of transmitters (with a slight variation of words and these are), that he (the narrator) said: " During any month continuously since he came to Medina."

وَحَدَّثَنَا مُحَمَّدُ بْنُ بَشَّارٍ وَأَبُو بَكْرِ بْنُ نَافِعٍ عَنْ غُنْدَرٍ عَنْ شُعْبَةَ عَنْ أَبِي بِشْرٍ بِهَذَا الْإِسْنَادِ وَقَالَ شَهْرًا مُتَتَابِعًا مُنْذُ قَدِمَ الْمَدِينَةَ

sunnah.com

'Uthman b. Hakim al-Ansari said: I asked Sa'id b. Jubair about fasting In Rajab, and we were then passing through the month of Rajab, whereupon he said: I heard Ibn 'Abbas (Allah be pleased with both of them) as saying: The Messenger of Allah used to observe fast (so continuously) that we (were inclined) to say that he would not break (them) and did not observe them so conti- nuously) that we (were inclined to say) that he would not observe fast.

حَدَّثَنَا أَبُو بَكْرِ بْنُ أَبِي شَيْبَةَ، حَدَّثَنَا عَبْدُ اللَّهِ بْنُ نُمَيْرٍ، ح وَحَدَّثَنَا ابْنُ نُمَيْرٍ، حَدَّثَنَا أَبِي، حَدَّثَنَا عُثْمَانُ بْنُ حَكِيمٍ الأَنْصَارِيُّ، قَالَ سَأَلْتُ سَعِيدَ بْنَ جُبَيْرٍ عَنْ صَوْمِ، رَجَبٍ - وَنَحْنُ يَوْمَئِذٍ فِي رَجَبٍ - فَقَالَ سَمِعْتُ ابْنَ عَبَّاسٍ - رضى الله عنهما - يَقُولُ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يَصُومُ حَتَّى نَقُولَ لاَ يُفْطِرُ ‏.‏ وَيُفْطِرُ حَتَّى نَقُولَ لاَ يَصُومُ ‏.‏

sunnah.com

The same hadith as the previous hadith has been transmitted through another chain.

وَحَدَّثَنِيهِ عَلِيُّ بْنُ حُجْرٍ، حَدَّثَنَا عَلِيُّ بْنُ مُسْهِرٍ، ح وَحَدَّثَنِي إِبْرَاهِيمُ بْنُ مُوسَى، أَخْبَرَنَا عِيسَى بْنُ يُونُسَ، كِلاَهُمَا عَنْ عُثْمَانَ بْنِ حَكِيمٍ، فِي هَذَا الإِسْنَادِ ‏.‏ بِمِثْلِهِ ‏.‏

sunnah.com