The Book of Fasting
13/27. Chapter:
Making up fasts on behalf of the deceased
Sahih Muslim
وَحَدَّثَنِيهِ إِسْحَاقُ بْنُ مَنْصُورٍ، أَخْبَرَنَا عُبَيْدُ اللَّهِ بْنُ مُوسَى، عَنْ سُفْيَانَ، بِهَذَا الإِسْنَادِ وَقَالَ صَوْمُ شَهْرَيْنِ .
This hadith has been narrated on the authority of Sufyan with the same chain of transmitters in which it is said: " Fasting of two months."
Reference : Sahih Muslim 1149dIn-book reference : Book 13, Hadith 206USC-MSA web (English) reference : Book 6, Hadith 2560