She informed him that the Messenger of Allah ﷺ swore that he would not enter upon some of his wives for a month. When twenty-nine days had passed, he came to them in the morning or in the evening.It was said to him, "Prophet of Allah, you swore not to enter upon them for a month."He replied, "The month is twenty-nine days."
حدثنا روح حدثنا ابن جريج قال أخبرني يحيى بن عبد الله بن محمد بن صيفي أن عكرمة بن عبد الرحمن أخبره أن
أخبرته أن رسول الله ﷺ حلف أن لا يدخل على بعض أهله شهرا فلما مضى تسعة وعشرون يوما غدا عليهم أو راح فقيل له حلفت يا نبي الله لا تدخل عليهم شهرا فقال إن الشهر تسعة وعشرون يوما
Its isnad is sahih. Yahya bin Abdullah bin Muhammad bin Sayfi is trustworthy, and his hadith is found in the collections of all six. The hadith has already appeared at length on the authority of Ayesha, and it is found in all the sahih collections.