Messenger of Allah ﷺ vowed to keep aloof from his wives for one month, and he had dislocation of his leg. So, he stayed in a Mashruba for 29 nights and then came down. Some people said, "O Messenger of Allah ﷺ! You vowed to stay aloof for one month," He replied, "The month is of 29 days."  

آلَى رَسُولُ اللَّهِ ﷺ مِنْ نِسَائِهِ وَكَانَتِ انْفَكَّتْ رِجْلُهُ فَأَقَامَ فِي مَشْرُبَةٍ تِسْعًا وَعِشْرِينَ لَيْلَةً ثُمَّ نَزَلَ فَقَالُوا يَا رَسُولَ اللَّهِ آلَيْتَ شَهْرًا فَقَالَ إِنَّ الشَّهْرَ يَكُونُ تِسْعًا وَعِشْرِينَ  

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  

Messenger of Allah ﷺ took an oath for abstention from his wives (for one month), and during those days he had a sprain in his foot. He stayed in a Mashrubah (an upper room) for twenty-nine nights and then came down. Then the people said, "O Messenger of Allah ﷺ! You took an oath for abstention (from your wives) for one month." On that he said, "A (lunar) month can be of twenty-nine days."  

آلَى رَسُولُ اللَّهِ ﷺ مِنْ نِسَائِهِ وَكَانَتِ انْفَكَّتْ رِجْلُهُ فَأَقَامَ فِي مَشْرُبَةٍ تِسْعًا وَعِشْرِينَ لَيْلَةً ثُمَّ نَزَلَ فَقَالُوا يَا رَسُولَ اللَّهِ آلَيْتَ شَهْرًا فَقَالَ {إِنَّ الشَّهْرَ يَكُونُ تِسْعًا وَعِشْرِينَ}  

"The Prophet swore an oath of abstention from his wives for a month and stayed in his room for twenty-nine days. It was said: 'O Messenger of Allah, did you not swear an oath of abstention for a month?' He said: 'This month is twenty-nine days.'"  

آلَى النَّبِيُّ ﷺ مِنْ نِسَائِهِ شَهْرًا فِي مَشْرَبَةٍ لَهُ فَمَكَثَ تِسْعًا وَعِشْرِينَ لَيْلَةً ثُمَّ نَزَلَ فَقِيلَ يَا رَسُولَ اللَّهِ أَلَيْسَ آلَيْتَ عَلَى شَهْرٍ قَالَ الشَّهْرُ تِسْعٌ وَعِشْرُونَ  

"The Messenger of Allah vowed to stay away from his wives for a month, so he stayed in a loft for twenty-nine days. They said: 'O Messenger of Allah, your vow was for a month,' so he said: 'The month is twenty-nine (days).'" (Using translation from Tirmidhī 690)   

أَنَّهُ قَالَ آلَى رَسُولُ اللَّهِ ﷺ مِنْ نِسَائِهِ وَكَانَتِ انْفَكَّتْ رِجْلُهُ فَأَقَامَ فِي مَشْرُبَةٍ تِسْعًا وَعِشْرِينَ ثُمَّ نَزَلَ قَالُوا يَا رَسُولَ اللَّهِ آلَيْتَ شَهْرًا قَالَ «الشَّهْرُ تِسْعٌ وَعِشْرُونَ»  

"The Prophet swore an oath of abstention from his wives for a month and stayed in his room for twenty-nine days. It was said: 'O Messenger of Allah, did you not swear an oath of abstention for a month?' He said: 'This month is twenty-nine days.'" (Using translation from Nasāʾī 3456)  

آلَى النَّبِيُّ ﷺ مِنْ نِسَائِهِ شَهْرًا فَقَعَدَ فِي مَشْرُبَةٍ لَهُ فَمَكَثَ تِسْعًا وَعِشْرِينَ لَيْلَةً ثُمَّ نَزَلَ فَقِيلَ يَا رَسُولَ اللهِ أَلَسْتَ آلَيْتَ عَلَى شَهْرٍ؟ قَالَ «الشَّهْرُ تِسْعٌ وَعِشْرُونَ»