Sahih Bukhari Volume 7, Book 68, Hadith 5293

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

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."