The Prophet ﷺ came in to me one day and asked, "Do you have anything to eat?"We said, "No."He said, "Then I am fasting."He came to us again on another day, and we said, "Messenger of Allah, we have been given some hays as a gift."He said, "Show it to me. I had begun the day fasting." Then he ate.
دخل علي النبي ﷺ ذات يوم فقال: هل عندكم شيء؟ فقلنا: لا. فقال: فإني إذن صائم. ثم أتانا يوما آخر فقلنا: يا رسول الله، أهدي لنا حيس، فقال: أرينيه، فلقد أصبحت صائما. فأكل.
Muslim narrated it in the Book of Fasting (1154:170) from Abu Bakr bin Abu Shayba, from Waki, from Talha bin Yahya, from his paternal aunt Ayesha bint Talha, from Ayesha, Mother of the Believers, who said, "..." and mentioned it.