Language:
كتاب النكاح
67  
Wedlock, Marriage (Nikaah)
(92)
Chapter: "Men are protectors and maintainers of women."
(91)
بَابُ قَوْلِ اللَّهِ تَعَالَى: {الرِّجَالُ قَوَّامُونَ عَلَى النِّسَاءِ بِمَا فَضَّلَ اللَّهُ بَعْضَهُمْ عَلَى بَعْضٍ} إِلَى قَوْلِهِ: {إِنَّ اللَّهَ كَانَ عَلِيًّا كَبِيرًا}
Sahih al-Bukhari 5201

Narrated Anas:

Allah's Messenger (ﷺ) took an oath that he would not visit his wives for one month, and he sat in an upper room belonging to him. Then, on the twenty ninth day he came down. It was said, "O Allah's Messenger (ﷺ)! You had taken an oath not to visit your wives for one month." He said, "The (present) month is of twenty-nine days."

حَدَّثَنَا خَالِدُ بْنُ مَخْلَدٍ، حَدَّثَنَا سُلَيْمَانُ، قَالَ حَدَّثَنِي حُمَيْدٌ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ آلَى رَسُولُ اللَّهِ صلى الله عليه وسلم مِنْ نِسَائِهِ شَهْرًا وَقَعَدَ فِي مَشْرُبَةٍ لَهُ فَنَزَلَ لِتِسْعٍ وَعِشْرِينَ فَقِيلَ يَا رَسُولَ اللَّهِ إِنَّكَ آلَيْتَ عَلَى شَهْرٍ‏.‏ قَالَ ‏ "‏ إِنَّ الشَّهْرَ تِسْعٌ وَعِشْرُونَ ‏"‏‏.‏
Reference : Sahih al-Bukhari 5201
In-book reference : Book 67, Hadith 135
USC-MSA web (English) reference : Vol. 7, Book 62, Hadith 129
  (deprecated numbering scheme)