1911. Narrated Anas: Allah’s Messenger, peace be upon him, vowed to keep aloof from his wives for one month, and he had dislocation of his leg. So, he stayed in a Mashrüba* for 29 nights and then came down. Some people said, “O Allah’s Messenger! You vowed to stay aloof for one month,” He replied, ”The month is of 29 days.”
*Attic room