It was narrated from 'Amr bin Shu'aib, from his father, that his grandfather said that the Prophet (ﷺ) said:
"Whoever swears an oath then sees that something else is better than it, let him not do it, and his leaving it is the expiation for it. " (JA)
English reference (JA): Vol. 3, Book 11, Hadith 2111 (JA)
Arabic reference (JA): Book 11, Hadith 2189 (JA)