This hadith has been narrated on the authority of Aswad b. Qais with the same chain of transmitters, but herein no mention has been made of the other month (consisting of) thirty days.
وَحَدَّثَنِيهِ مُحَمَّدُ بْنُ حَاتِمٍ، حَدَّثَنَا ابْنُ مَهْدِيٍّ، عَنْ سُفْيَانَ، عَنِ الأَسْوَدِ بْنِ قَيْسٍ، بِهَذَا الإِسْنَادِ وَلَمْ يَذْكُرْ لِلشَّهْرِ الثَّانِي ثَلاَثِينَ .
Muslim
The Book of Fasting • Hadith 18