(4) باب الشَّهْرِ يَكُونُ تِسْعًا وَعِشْرِينَ
Narrated Abu Bakrah:
The Prophet (ﷺ) as saying: The two months of 'Id (festival), Ramadan and Dhu al-Hijjah, are not defective.
Reference: Sunan Abi Dawud 2323
In-book reference: Book 14, Hadith 11
English translation: Book 13, Hadith 2316