Sahih Muslim 4291
صحيح مسلم#4291SahihHammam b. Munabbih reported:This is what Abu Huraira reported to us from Allah's Messenger (ﷺ), and he narrated a hadith and (one) of them is that Allah's Messenger (ﷺ) said: I swear by Allah, it is more sinful in Allah's sight for one of you to persist in an oath regarding his family than payment of its expiation which Allah has imposed upon him (for breaking the oath)
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 27:38