The Book of Fasting
13/34. Chapter:
The Prophet's Fasts at times other than Ramadan; and it is recommended to ensure that no month is free of fasting
Sahih Muslim
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 .
The same hadith as the previous hadith has been transmitted through another chain.
Reference : Sahih Muslim 1157dIn-book reference : Book 13, Hadith 233USC-MSA web (English) reference : Book 6, Hadith 2586