Messenger of Allah 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 Messenger of Allah ﷺ! You took an oath to abstain from your wives for one month." He said, "The month is of twenty nine days."  

أَنَّهُ سَمِعَ أَنَسَ بْنَ مَالِكٍ يَقُولُ آلَى رَسُولُ اللَّهِ ﷺ مِنْ نِسَائِهِ وَكَانَتِ انْفَكَّتْ رِجْلُهُ فَأَقَامَ فِي مَشْرُبَةٍ لَهُ تِسْعًا وَعِشْرِينَ ثُمَّ نَزَلَ فَقَالُوا يَا رَسُولَ اللَّهِ آلَيْتَ شَهْرًا فَقَالَ الشَّهْرُ تِسْعٌ وَعِشْرُونَ  

Ibn ʿUmar used to say about the Ila (which Allah defined (in the Holy Book), "If the period of Ila expires, then the husband has either to retain his wife in a handsome manner or to divorce her as Allah has ordered."  

أَنْ يُمْسِكَ بِالْمَعْرُوفِ أَوْ يَعْزِمَ بِالطَّلاَقِ كَمَا أَمَرَ اللَّهُ ﷻ  

"When the period of four months has expired, the husband should be put in prison so that he should divorce his wife, but the divorce does not occur unless the husband himself declares it. This has been mentioned by ʿUthman, ʿAli, Abu Ad-Darda, ʿAisha and twelve other companions of the Prophet ﷺ ."  

عَنْ عُثْمَانَ وَعَلِيٍّ وَأَبِي الدَّرْدَاءِ وَعَائِشَةَ وَاثْنَىْ عَشَرَ رَجُلاً مِنْ أَصْحَابِ النَّبِيِّ ﷺ