Sahih Muslim 1102
Sahih Muslim · Book 13: The Book of Fasting · The prohibition of Al-Wisal
A hadith like this has been transmitted by Ibn 'Umar (Allah be pleased with both of them), but he did not make mention of (the words):
وَحَدَّثَنَا عَبْدُ الْوَارِثِ بْنُ عَبْدِ الصَّمَدِ ، حَدَّثَنِي أَبِي ، عَنْ جَدِّي ، عَنْ أَيُّوبَ ، عَنْ نَافِعٍ ، عَنِ ابْنِ عُمَرَ ، - رضى الله عنهما - عَنِ النَّبِيِّ صلى الله عليه وسلم بِمِثْلِهِ وَلَمْ يَقُلْ فِي رَمَضَانَ .
" During the month of Ramadan."