The ruling on one who has intercourse in Ramadan while thinking it is still night

Question:
I am a man who had intercourse with my wife on one of the days of the blessed month of Ramadan, and I thought that it was still night and that the time for abstaining had not yet arrived. When I finished my need and opened the door of my room, I found that the sun had risen and the day had begun. So I performed the full ritual bath and continued my fast. Is my fast accepted? And what is obligatory for me to do?

Answer:
You must make up the fast, and you must pay the expiation; because you were negligent, you did not take precaution, and you did not look. So you must make up the day and pay the expiation for the intercourse, and it is the same for her; because you both had intercourse during the day.