Narrated by:'Abdur-Rahman bin Samurah said
It was narrated that 'Abdur-Rahman bin Samurah said:"The Prophet said to me: 'If you swear an oath, and you see something that is better, then do that which is better and offer expiation for your oath.'"
أَخْبَرَنَا زِيَادُ بْنُ أَيُّوبَ، قَالَ حَدَّثَنَا هُشَيْمٌ، قَالَ أَنْبَأَنَا مَنْصُورٌ، وَيُونُسُ، عَنِ الْحَسَنِ، عَنْ عَبْدِ الرَّحْمَنِ بْنِ سَمُرَةَ، قَالَ قَالَ لِي النَّبِيُّ صلى الله عليه وسلم " إِذَا آلَيْتَ عَلَى يَمِينٍ فَرَأَيْتَ غَيْرَهَا خَيْرًا مِنْهَا فَأْتِ الَّذِي هُوَ خَيْرٌ وَكَفِّرْ عَنْ يَمِينِكَ " .
Nesai
The Book of Oaths and Vows • Hadith 3789