The Messenger of Allah ﷺ swore to abstain from some of his wives for a month. When twenty-nine days had passed, he went to them in the morning, or in the evening. It was said, "Messenger of Allah, only twenty-nine days have passed."He replied, "The month is twenty-nine days."
حدثنا أحمد بن يوسف السلمي حدثنا أبو عاصم عن ابن جريج عن يحيى بن عبد الله بن محمد بن صيفي عن عكرمة بن عبد الرحمن
أن رسول الله ﷺ آلى من بعض نسائه شهرا فلما كان تسعة وعشرين راح أو غدا فقيل يا رسول الله إنما مضى تسع وعشرون فقال الشهر تسع وعشرون
Bukhari narrated it in the Book of Fasting, chapter titled "The saying of the Prophet ﷺ, 'When you see the new moon, fast, and when you see it, break your fast,'" no. 1910, 5202, and Muslim narrated it in the Book of Fasting, chapter titled "The month may consist of twenty-nine days," no. 1085, from the hadith of Abu Asim Dahhak bin Makhlad, through this route.