Sunan Ibn Majah, Book 7, Hadith 1728 (In-Book) ⓘ
It was narrated that from ‘Abdur-Rahman bin Abu Bakrah, from his father, that the Prophet said: “Two months of ‘Eid whose reward cannot be reduced (even if they are twenty-nine days): ‘Ramaadan and Dhul-Hijjah.”
حَدَّثَنَا حُمَيْدُ بْنُ مَسْعَدَةَ، حَدَّثَنَا يَزِيدُ بْنُ زُرَيْعٍ، حَدَّثَنَا خَالِدٌ الْحَذَّاءُ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ أَبِي بَكْرَةَ، عَنْ أَبِيهِ، عَنِ النَّبِيِّ ـ صلى الله عليه وسلم ـ قَالَ " شَهْرَا عِيدٍ لاَ يَنْقُصَانِ رَمَضَانُ وَذُو الْحِجَّةِ " .
also referenced under: Hadith 1659 (Reference) & Volume 2, Book 7, Hadith 1659 (DarusSalam)