صحيح البخاري

Narrated Anas:

Allah's Messenger (ﷺ) took an oath that he would not go to his wives for one month as his foot had been sprained. He stayed in an upper room when `Umar went to him and said, "Have you divorced your wives?" He said, "No, but I have taken an oath that I would not go to them for one month." The Prophet stayed there for twenty-nine days, and then came down and went to his wives.