It is recommended for the one who swears an oath then sees that something else is better than it; To do that which is better and offer expiation for his oath
حَدَّثَنِي مُحَمَّدُ بْنُ عَبْدِ اللَّهِ بْنِ نُمَيْرٍ، وَمُحَمَّدُ بْنُ طَرِيفٍ الْبَجَلِيُّ، - وَاللَّفْظُ لاِبْنِ طَرِيفٍ - قَالاَ حَدَّثَنَا مُحَمَّدُ بْنُ فُضَيْلٍ، عَنِ الأَعْمَشِ، عَنْ عَبْدِ الْعَزِيزِ بْنِ رُفَيْعٍ، عَنْ تَمِيمٍ الطَّائِيِّ، عَنْ عَدِيٍّ، قَالَ قَالَ رَسُولُ اللَّهِ صلى الله عليه وسلم " إِذَا حَلَفَ أَحَدُكُمْ عَلَى الْيَمِينِ فَرَأَى خَيْرًا مِنْهَا فَلْيُكَفِّرْهَا وَلْيَأْتِ الَّذِي هُوَ خَيْرٌ " .
'Adi reported Allah's Messenger (ﷺ) as saying: When anyone amongst you takes an oath, but he finds (something) better than that he should expiate (the breaking of the oath), and do that which is better.