Abu Hurairah (May Allah be pleased with him) said:
The Messenger of Allah (ﷺ) said, "Persistence in respect of his oath about his family is more sinful with Allah than the payment of its expiation prescribed by Allah."[Al-Bukhari and Muslim]. (DE)
App reference (DE): Book 18, Hadith 208 (DE)
Arabic/English book reference (DE): Book 18, Hadith 1718 (DE)