The Prophet ﷺ said, "Whoever swears an oath and then sees that something else is better than it, then abandoning that oath is its expiation."
حدثنا عبد الصمد حدثنا خليفة بن خياط الليثي
عن النبي ﷺ قال من حلف على يمين فرأى غيرها خيرا منها فهي كفارتها
Its chain of transmission is sahih, and it is a repetition of 6736. See also 6907.