Sahih al-Bukhari 5289
Sahih al-Bukhari · Book 68: Divorce · "Those who take an oath, not to have sexual relations with their wives, must wait four months."
Narrated Anas bin Malik:
حَدَّثَنَا إِسْمَاعِيلُ بْنُ أَبِي أُوَيْسٍ ، عَنْ أَخِيهِ ، عَنْ سُلَيْمَانَ ، عَنْ حُمَيْدٍ الطَّوِيلِ ، أَنَّهُ سَمِعَ أَنَسَ بْنَ مَالِكٍ ، يَقُولُ آلَى رَسُولُ اللَّهِ صلى الله عليه وسلم مِنْ نِسَائِهِ، وَكَانَتِ انْفَكَّتْ رِجْلُهُ فَأَقَامَ فِي مَشْرُبَةٍ لَهُ تِسْعًا وَعِشْرِينَ، ثُمَّ نَزَلَ فَقَالُوا يَا رَسُولَ اللَّهِ آلَيْتَ شَهْرًا. فَقَالَ " الشَّهْرُ تِسْعٌ وَعِشْرُونَ " .
Allah's Messenger (ﷺ) took an oath that he would abstain from his wives, and at that time his leg had been sprained (dislocated). So he stayed in the Mashruba (an attic room) of his for 29 days. Then he came down, and they (the people) said, "O Allah's Messenger (ﷺ)! You took an oath to abstain from your wives for one month." He said, "The month is of twenty nine days."