Amir ibn Mas’ud (may Allah be pleased with him) narrated that the Messenger of Allah (ﷺ) said, "The cool booty is fasting in winter." [Narrated by Ahmad and Tirmidhi] Tirmidhi said, "This is a mursal hadith."
Abu Hurairah (may Allah be pleased with him) narrated that the Messenger of Allah (ﷺ) said, "Everything has a form of charity, and the charity of the body is fasting."