3844An NasaiSahih (Darussalam)أَخْبَرَنَا مُحَمَّدُ بْنُ مَنْصُورٍ، قَالَ حَدَّثَنَا سُفْيَانُ، عَنْ أَيُّوبَ، عَنْ نَافِعٍ، عَنِ ابْنِ عُمَرَ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم مَنْ حَلَفَ فَقَالَ إِنْ شَاءَ اللَّهُ فَقَدِ اسْتَثْنَى " It was narrated that Ibn 'Umar said:"The Messenger of Allah said: 'Whoever swears an oath and says: If Allah wills, then he has made an exception.'"Reference: Sunan an-Nasa'i 3829 In-book : Book 35, Hadith 69 English translation : Vol. 4, Book 35, Hadith 3860