(7) باب فِي الطَّلاَقِ قَبْلَ النِّكَاحِ
The above tradition has also been transmitted by 'Amr bin Shu'aib through a different chain of narrators to the same effect. This version adds "If anyone swears an oath to do an act of disobedience to GOD, his oath is not valid, and if anyone swears an oath to sever relationship, his oath is not valid(i.e., he must not fulfill it)
Reference: Sunan Abi Dawud 2191
In-book reference: Book 13, Hadith 17
English translation: Book 12, Hadith 2186