Ayesha reported,

Ayesha reported that the Messenger of Allah ﷺ said to her one day, "Ayesha, do you have anything to eat?"She said, "I replied, 'Messenger of Allah, we have nothing.'"He said, "Then I am fasting."She continued, "The Messenger of Allah ﷺ went out, and a gift was brought to us, or some visitors came to see us. When the Messenger of Allah ﷺ returned, I said, 'Messenger of Allah, a gift was brought to us, or visitors came, and I have set aside something for you.'"He asked, "What is it?"I said, "Hays."He said, "Bring it here." So I brought it to him and he ate. Then he said, "I had begun the day fasting."Talha said, I related this hadith to Mujahid, and he said, "That is like a man who sets aside charity from his wealth. If he wishes, he gives it, and if he wishes, he keeps it."

عن عائشة أم المؤمنين قالت

قال لي رسول الله ﷺ ذات يوم: يا عائشة هل عندكم شيء؟ قالت: فقلت: يا رسول الله، ما عندنا شيء. قال: فإني صائم. قالت: فخرج رسول الله ﷺ فأهديت لنا هدية أو جاءنا زور. قالت: فلما رجع رسول الله ﷺ. قلت: يا رسول الله، أهديت لنا هدية أو جاءنا زور- وقد خبات لك شيئا. قال: ما هو؟ قلت: حيس. قال: هاتيه فجئت به فأكل. ثم قال: قد كنت أصبحت صائما. قال طلحة: فحدثت مجاهدا بهذا الحديث. فقال: ذاك بمنزلة الرجل يخرج الصدقة من ماله. فإن شاء أمضاها وإن شاء أمسكها.