Sahih Muslim 9861
In-book no 2584وَحَدَّثَنِيهِ 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."