Reference: Fataawa al-Lajnah ad-Daa.imah lil-Buhooth al-‘Ilmiyyah wal-Iftaa. – Fatwa No.4181
Fataawa Ramadhaan – Volume 2, Page 569, Fatwa No.552
Question: I awoke one morning, half-asleep, and went to the kitchen and quickly ate some food but when I began to eat, I looked at the clock and found the time to be 4.40am. The time for the Fajr prayer, here in Tabuk (northern Saudi Arabia), is 4.15am. So, at that time I stopped eating and began fasting. Knowing I had eaten three or four spoonfuls, do I have to make up this fast or not, O Shaykh?
Response: If the situation is as mentioned then it is obligatory upon you to make up the fast because you ate after the time of Fajr had entered.
And with Allaah lies all the success, and may Allaah send prayers and salutations upon our Prophet Muhammad ﷺ and his family and his companions.