What is the ruling on a man who has intercourse with his wife after her menstrual period stops, then discovers that the period had not actually stopped?

Question:
He says: I had intercourse with my wife after her menstrual period stopped, then we discovered that the period had not stopped. What is the ruling? And is there anything required of me?

Answer:
Yes, you made a mistake in that you hastened. Allah, Glorified and Exalted is He, has permitted intercourse on two conditions. The first condition is the complete cessation of the blood, when you see the complete purity after which there is nothing. The second matter is the full ritual bath. That is, when the menstruation stops, and if they purify themselves, meaning by the full ritual bath, and since you had intercourse before the menstruation ended, and you found its traces, you must repent and seek forgiveness, and you owe an expiation, which is the equivalent of a mithqal of gold or half a mithqal. A mithqal of gold or half a mithqal: you ask the goldsmiths about it, and they will tell you its value and weight. Yes.