be to Allaah.
If a man has intercourse with his wife and does not know
that she is menstruating, then there is no blame on him. It says in a
hadeeth narrated from Abu Dharr al-Ghifaari that the Messenger of Allaah
SAWS (peace and blessings of Allaah be upon him) said, “Allaah will
forgive my ummah for their mistakes, what they forget and what they are
forced to do.” (Narrated by Ibn Maajah, al-Talaaq, 2033; classed as
saheeh by al-Albaani in Saheeh Sunan Ibn Maajah, 1662).
But the wife should tell
him of her situation and let him know that she is bleeding in menstruation,
because a man may not realize that and he may have intercourse with her
whilst she is menstruating, which is haraam according to sharee’ah. In that
case the sin is on her. Menstrual blood is something that is well known to
women, and when it starts the woman is considered to be menstruating.
If what happened happened without either
party knowing, then they are not sinners, because they did not know and they
did not do it deliberately. And Allaah knows best.