The Book of Oaths and Vows
35/16. Chapter:
Expiation After Breaking An Oath
Sunan an-Nasai
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 " .
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.'"
Reference : Sunan an-Nasa'i 3789In-book reference : Book 35, Hadith 29English translation : Vol. 4, Book 35, Hadith 3820