(43) باب الاِسْتِثْنَاءِ .
It was narrated that Abu Hurairah 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 3855
In-book reference: Book 35, Hadith 95
English translation: Vol. 4, Book 35, Hadith 3886