Umar bin Khattab reported,

When the Messenger of Allah ﷺ withdrew from his wives, I said, "Messenger of Allah, you have only been in the chamber for twenty-nine days."The Messenger of Allah ﷺ replied, "The month consists of twenty-nine days."

Azami 4330

Sahih

عن عمر بن الخطاب، قال

لما اعتزل رسول الله ﷺ نساءه قلت: يا رسول الله، إنما كنت فى الغرفة تسعا وعشرين؟ فقال رسول الله ﷺ: إن الشهر تسعا وعشرين.

الأعظمي 4330صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Fasting
Chapter
Obligation of fasting, its virtue, and its rulings
Section
Month can be twenty-nine days
Numbering
Jami al-Kamil 4330 (2nd edition)
Azami 4330