It was narrated from 'Adi bin Hatim that :
the Messenger of Allah (ﷺ), said: "Whoever swears an oath then sees that something else is better than it, let him do that which is better and offer expiation for what he swore about. " (IT)
English reference (IT): Vol. 3, Book 11, Hadith 2108 (IT)
Arabic reference (IT): Book 11, Hadith 2186 (IT)