Hadith 930

Narrated 'Aishah (RA): Allah's Messenger (ﷺ) swore that he would stay away from his wives for a period. He made something unlawful (for himself) (i.e. something not in itself unlawful). So, he made the lawful unlawful, and he made atonement for breaking an oath. [Reported by at-Tirmidhi, and its narrators are reliable (thiqah)].