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." (Using translation from Bukhārī 1911)   

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

[Machine] The pre-Islamic period of Ignorance (jahiliyyah) used to consider the year as consisting of twelve months, and sometimes even more than that. But Allah ﷻ reduced them to four sacred months. So, if someone's veneration (i.e. his intention to observe sacredness and respect) was specifically for these four months, and in another narration, Yunus said, "If someone's veneration was for less than four months, then it is not considered veneration." Ata also said, "And if he inclines towards it while it is in her family's home before marrying her, then it is not considered veneration."  

كَانَ إِيلَاءُ أَهْلِ الْجَاهِلِيَّةِ السَّنَةُ وَالسَّنَتَيْنِ وَأَكْثَرُ مِنْ ذَلِكَ فَوَقَّتَ اللهُ ﷻ لَهُمْ أَرْبَعَةَ أَشْهُرٍ فَإِنْ كَانَ إِيلَاؤُهُ وَفِي رِوَايَةِ يُونُسَ فَمَنْ كَانَ إِيلَاؤُهُ أَقَلَّ مِنْ أَرْبَعَةِ أَشْهُرٍ فَلَيْسَ بِإِيلَاءٍ قَالَ وَقَالَ عَطَاءٌ وَإِنْ آلَى مِنْهَا وَهِيَ فِي بَيْتِ أَهْلِهَا قَبْلَ أَنْ يَبْنِيَ بِهَا فَلَيْسَ بِإِيلَاءٍ  

[Machine] That it should never touch her or six months or more or what exceeds four months or something like that  

أَنْ لَا يَمَسَّهَا أَبَدًا أَوْ سِتَّةَ أَشْهُرٍ أَوْ أَكْثَرَ أَوْ مَا زَادَ عَلَى أَرْبَعَةِ أَشْهُرٍ أَوْ نَحْوَ ذَلِكَ