The Messenger of Allah ﷺ offered me something to eat, and I said, "I am fasting."He replied, "And so am I."
حدثنا يحيى بن زكريا قال أخبرني أبي عن سعد بن إبراهيم عن رجل من قريش من بني تيم يقال له طلحة
تناولني رسول الله ﷺ فقلت إني صائمة فقال وأنا صائم
Its isnad is sahih. Talha is Ibn Abdullah bin Uthman Taymi, and he is trustworthy, his hadith being found in Bukhari. The hadith has already appeared at 24903.