Ibn Sa'd محمد بن سعد البغدادي · The Book of Fasting

"The Messenger of Allah said: "The Messenger of Allah said: Do not fast before Ramadan. Fast when you see it and stop fasting when you see it, and if clouds prevent you from seeing it, then complete Thirty (Days)."'

"The Messenger of Allah swore not to come to his wives for a month, and twenty-nine days passed. I said: 'Did you not wives to keep away from you wives for a month? I have counted twenty-nine days.' The Messenger of Allah said: 'The month is twenty-nine days."'

"I was very keen to ask 'Umar bin Al-Khattab about the two wives of the Messenger of Allah to whom Allah said: If you two turn in repentance to Allah, (it will be better for you), your hearts are indeed so inclined." And he quoted the Hadith. He said concerning it:' "The from his wives for twenty-nine days because of that, when Hafsah had made her disclosure to Aishah. He had said: 'I will not enter upon them for a…