(4) باب الشَّهْرِ يَكُونُ تِسْعًا وَعِشْرِينَ
Narrated Abdullah ibn Mas'ud:
We kept fast for twenty-nine days along with the Prophet (ﷺ) more often than we kept fast for thirty days. (IT)
Reference (IT): Sunan Abi Dawud 2322 (IT)
In-book reference (IT): Book 14, Hadith 10 (IT)
English translation (IT): Book 13, Hadith 2315 (IT)