The Messenger of Allah ﷺ withdrew from his wives, having sprained his foot, and he stayed in an upper chamber of his for twenty-nine days. Then he came down, and they said, "Messenger of Allah, you swore to stay away for a month?"He replied, "A month can be twenty-nine days."
الى رسول الله ﷺ من نسائه، وكان انفكت رجله، فأقام في مشربة له تسعا وعشرين، ثم نزل، فقالوا: يا رسول الله، آليت شهرا؟ فقال: الشهر يكون تسع وعشرون.
Bukhari narrated it in the Book of Divorce (5289) from Ismail bin Abu Uways, from his brother, from Sulayman, from Humayd Tawil, that he heard Anas bin Malik say what has already been mentioned. He also narrated it in the Book of Prayer (378) through another route from Humayd Tawil, at greater length.