Sahih Muslim | Book 15 | Hadith Number 4071

Narrated by Hammam b. Munabbih
Hammam b. Munabbih reported: This is what Abu Huraira reported to us from Allah's Messenger (may peace be upon him), and he narrated a hadith and (one) of them is that Allah's Messenger (may peace be upon him) 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).