The Book of Oaths (Kitab Al-Aiman)

Muslim :: Book 15 : Hadith 4071

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).

Source materials are from the University of Southern California MSA site
Hadith eBooks converted from Imaan Star