وَحَدَّثَنِي يَحْيَى، عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ عُمَرَ بْنَ الْخَطَّابِ، وَعَبْدَ اللَّهِ بْنَ عُمَرَ، وَعَبْدَ اللَّهِ بْنَ مَسْعُودٍ، وَسَالِمَ بْنَ عَبْدِ اللَّهِ، وَالْقَاسِمَ بْنَ مُحَمَّدٍ، وَابْنَ، شِهَابٍ وَسُلَيْمَانَ بْنَ يَسَارٍ كَانُوا يَقُولُونَ إِذَا حَلَفَ الرَّجُلُ بِطَلاَقِ الْمَرْأَةِ قَبْلَ أَنْ يَنْكِحَهَا ثُمَّ أَثِمَ إِنَّ ذَلِكَ لاَزِمٌ لَهُ إِذَا نَكَحَهَا ‏.‏

Yahya related to me from Malik that he had heard that Umar ibnal-Khattab, Abdullah ibn Umar, Abdullah ibn Masud, Salim ibn Abdullah,al-Qasim ibn Muhammad, Ibn Shihab,and Sulayman ibn Yasar all said, "Ifa man has vowed to divorce his wife before marrying her and then hebreaks his vow, divorce is obligatory for him when he marries her." Translation Not Available

Book Ref: Muwatta Imam Malik Book 29 Hadith 1234
Web Ref:  Muwatta Imam Malik Book 29 Hadith 73