If one intends to fast and abstains before the time of Fajr enters, does this invalidate his fast?

Question:
Honorable Shaykh, may Allah grant you success. He says: If a person hears the adhan, then learns that the mu'adhdhin called before the time had entered, and upon learning this, the fasting person continued his fast, does this invalidate the fast?

Answer:
No, it does not break it. It does not invalidate the fast, even if he fasted before the dawn appeared. However, it is contrary to what is best and preferable.