Sayyiduna Adi bin Hatim (may Allah be pleased with him) said: I heard the Messenger of Allah (peace and blessings be upon him) saying: "Whoever swears an oath and then sees something else better than it, let him adopt what is better and make expiation for his oath."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 14299