Ibn ‘Abbas reported God’s Messenger as saying, “If anyone takes a vow but does not name it, its atonement is the same as that for an oath; if anyone takes a vow to do an act of disobedience, its atonement is the same as that for an oath; if anyone takes a vow he is unable to fulfil, its atonement is the same as that for an oath; but if anyone takes a vow he is able to fulfil, he must do so.” Abu Dawud and Ibn Majah transmitted it, but some traced it no farther back than Ibn ‘Abbas.
Hadith Referenceمشكوة المصابيح / كتاب الإيمان والنذور / 3436
Hadith Gradingالألبانی:لم تتمّ دراسته | زبیر علی زئی:إسناده حسن
Hadith Takhrij´تحقيق و تخريج: محدث العصر حافظ زبير على زئي رحمه الله` «إسناده حسن، رواه أبو داود (3322) و ابن ماجه (2128)»