Does one sin who wakes late for Fajr prayer, and thinks he will catch it before sunrise, then is surprised by the entry of the sunrise time while he is performing ablution?

If you continue to sleep after hearing the Iqamah (definition) for Fajr prayer, knowing that you will not wake up before the time expires, then you are sinful. And if you remain awake in your sleeping place until the prayer time has expired, you have committed a grave sin. You must repent from intentionally delaying the prayer until its time expires without a valid شرعي (legally permissible) excuse, because it is one of the major sins. It must also be noted that congregational prayer in the mosque is obligatory according to a group of scholars for an able-bodied man who hears the call.