The Mother of the Believers, Sayyidah Aishah (may Allah be pleased with her), says that (the Prophet (peace and blessings be upon him)) used to love (a certain) food. One day he (peace and blessings be upon him) came and said: "Do you have (that) food?" I said: No. So he (peace and blessings be upon him) said: "Then I am fasting."
In one narration: He (peace and blessings be upon him) would come to us and say: "Do you have any morning meal?" If I said no, he (peace and blessings be upon him) would say: "Then I am fasting."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصيام / 7914