(34) بَاب صِيَامِ النَّبِيِّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ فِي غَيْرِ رَمَضَانَ وَاسْتِحْبَابِ أَنْ لَا يُخْلِيَ شَهْرًا عَنْ صَوْمٍ
'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 (ﷺ) 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.
Reference: Sahih Muslim 1157 c
In-book reference: Book 13, Hadith 232
USC-MSA web (English) reference(deprecated numbering scheme): Book 6, Hadith 2585