Chapter: "Start observing Saum on seeing the crescent of Ramadan, and stop on seeing the crescent (of Shawwal)."
Narrated Anas:Allah's Messenger (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 Allah's Messenger (ﷺ)! You vowed to stay aloof for one month," He replied, "The month is of 29 days."
Reference
Sahih al-Bukhari 1911
In-book reference
Book 30, Hadith 21
USC-MSA web (English)
Vol. 3, Book 31, Hadith 135
Translation by Dr. M. Muhsin Khan · Language: EN
Sahih
Arabic Text
حَدَّثَنَا عَبْدُ الْعَزِيزِ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا سُلَيْمَانُ بْنُ بِلاَلٍ، عَنْ حُمَيْدٍ، عَنْ أَنَسٍ ـ رضى الله عنه ـ قَالَ آلَى رَسُولُ اللَّهِ صلى الله عليه وسلم 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 ".