It was reported from the Prophet ﷺ that he said, "The month is twenty-nine days."This was mentioned to Ayesha, and she said, "May Allah have mercy on Abu Abdul-Rahman. Did the Messenger of Allah ﷺ not withdraw from his wives for a month, then come down after twenty-nine days? When this was pointed out to him, he said, 'A month may be twenty-nine days.'"
حدثنا يحيى بن سعيد عن محمد بن عمرو أخبرني يحيى بن عبد الرحمن
عن النبي ﷺ قال الشهر تسع وعشرون فذكروا ذلك لعائشة فقالت يرحم الله أبا عبد الرحمن وهل هجر رسول الله ﷺ نساءه شهرا فنزل لتسع وعشرين فقيل له فقال إن الشهر قد يكون تسعا وعشرين