Bulugh al-Maram #765

'A’isha (RAA) narrated, ‘One day the Messenger of Allah (ﷺ) entered my house and said, “ls there anything here (to eat)?" I said, ‘NO,’ He said, “I shall then be fasting (today)." Then he came to us another day and we said to him, 'Someone has offered us some hais as a gift.’ He then said, "Show it to me. I had been fasting since this morning, “and he ate from it ( as it was a voluntary fast and not during the obligatory fasting of Ramadan). Related by Muslim.