Language:
كتاب الطلاق
68
Divorce
(21)
Chapter: "Those who take an oath, not to have sexual relations with their wives, must wait four months."
(21)
بَابُ قَوْلِ اللَّهِ تَعَالَى: {لِلَّذِينَ يُؤْلُونَ مِنْ نِسَائِهِمْ تَرَبُّصُ أَرْبَعَةِ أَشْهُرٍ} إِلَى قَوْلِهِ: {سَمِيعٌ عَلِيمٌ} {فَإِنْ فَاءُوا} رَجَعُوا
Sahih al-Bukhari 5291

Ibn `Umar added:

"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 `Uthman, `Ali, Abu Ad-Darda, `Aisha and twelve other companions of the Prophet (ﷺ) ."

وَقَالَ لِي إِسْمَاعِيلُ حَدَّثَنِي مَالِكٌ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، إِذَا مَضَتْ أَرْبَعَةُ أَشْهُرٍ يُوقَفُ حَتَّى يُطَلِّقَ، وَلاَ يَقَعُ عَلَيْهِ الطَّلاَقُ حَتَّى يُطَلِّقَ‏.‏ وَيُذْكَرُ ذَلِكَ عَنْ عُثْمَانَ وَعَلِيٍّ وَأَبِي الدَّرْدَاءِ وَعَائِشَةَ وَاثْنَىْ عَشَرَ رَجُلاً مِنْ أَصْحَابِ النَّبِيِّ صلى الله عليه وسلم‏.‏
Reference : Sahih al-Bukhari 5291
In-book reference : Book 68, Hadith 40
USC-MSA web (English) reference : Vol. 7, Book 63, Hadith 213
  (deprecated numbering scheme)