Anas bin Malik reported,

The Messenger of Allah ﷺ took an oath to abstain from his wives, and his foot had been sprained, so he stayed in an upper chamber for twenty-nine nights. Then he came down, and they said, "Messenger of Allah, you swore to abstain for a month."He replied, "A month can be twenty-nine days."

Bukhari 1911

Sahih

حدثنا عبد العزيز بن عبد الله حدثنا سليمان بن بلال عن حميد

عن أنس رضي الله عنه قال

آلى رسول الله ﷺ من نسائه وكانت انفكت رجله فأقام في مشربة تسعا وعشرين ليلة ثم نزل فقالوا يا رسول الله آليت شهرا فقال إن الشهر يكون تسعا وعشرين

البخاري 1911صحيح
Contents
Reference
Commentary
Ayat
Collection
Sahih Bukhari
Book
Fasting
Chapter
Prophet ﷺ saying, "When you see the Hilal, fast, and when you see it, break your fast"
Numbering
Darussalam 1911
Bukhari 1911