The Messenger of Allah ﷺ withdrew from his wives for a month. When twenty-nine days had passed, Jibreel came to him and said, "Your oath has been fulfilled and the month is complete."
حدثنا عمرو بن محمد أبو سعيد العنقزي أخبرنا سفيان عن سلمة بن كهيل عن عمران
هجر رسول الله ﷺ نساءه شهرا فلما مضى تسع وعشرون أتاه جبريل فقال قد برت يمينك وقد تم الشهر
Its isnad is sahih. Amr bin Muhammad Naqidi has already appeared at number 3, and he is trustworthy, one of the teachers of Ahmad. Imran is Ibn Harith Abu Hakam Sulami, and the hadith is given in fuller form at 1885. See also 1985, and see also what has already passed in the Musnad of Umar, 222.