I heard the Messenger of Allah ﷺ say, "Whoever fasts a single day in the path of Allah, Allah will distance his face from the Fire by seventy autumns."
سمعت رسول الله ﷺ يقول: من صام يوما في سبيل الله باعد الله وجهه عن النار سبعين خريفا.
Bukhari related it in the Book of Jihad and Expeditions (2840), and Muslim in the Book of Fasting (1153:168), both through the route of Abdul-Razzaq, who said, Ibn Jurayj informed us, who said, Yahya bin Saeed and Suhayl bin Abu Salih informed me, that they both heard Numan bin Abu Ayyash Zurqi narrating from Abu Saeed Khudri, and he related it. Their wording is identical, except that Bukhari said, "afterward."