Question:Where in the Bible does it talk about a women monthly cycle and that a man should not be with her while she is on her monthly? My man and I where having a Bible discussion yesterday and he said he read something about that in the Bible but he could not remember were. I have read the Bible from beginning to end but don't remember reading that, but it not to say it not in there.
Your man has the better memory. The laws regarding menstrual periods are in the Old Law, given to the Israelites, and fall in the category of the uncleanness laws. Before going further, it would be good for you to first understand what the uncleanness laws were about. Many people misunderstand them. Take a look at the article "Uncleanness" to learn more.
To get His point across, God selected several things from life which were called unclean. All of them share the characteristic of being at least slightly gross to most people. Some of them were things a person could avoid by being careful, but some things could not be avoided. For instance, touching a dead body made a person unclean for a week, but at the same time God said that the dead had to be buried. Thus in the fulfillment of a command, a person became unclean for a while. Others were things that could not be avoided. For women it was was their monthly periods. They were unclean during the time of their blood flow. These same monthly periods were something men could avoid and were expected to avoid.
"If a woman has a discharge, and the discharge from her body is blood, she shall be set apart seven days; and whoever touches her shall be unclean until evening. Everything that she lies on during her impurity shall be unclean; also everything that she sits on shall be unclean. Whoever touches her bed shall wash his clothes and bathe in water, and be unclean until evening. And whoever touches anything that she sat on shall wash his clothes and bathe in water, and be unclean until evening. If anything is on her bed or on anything on which she sits, when he touches it, he shall be unclean until evening. And if any man lies with her at all, so that her impurity is on him, he shall be unclean seven days; and every bed on which he lies shall be unclean" (Leviticus 15:19-24).
"Also you shall not approach a woman to uncover her nakedness as long as she is in her customary impurity" (Leviticus 18:19).
Thus a casual contact with the woman or her bedding would make a man unclean for a day, but sex during the blood flow would make him unclean for a whole week. If it was done purposely, that is he knew she was unclean but they decided to have sex anyway, then it resulted in exile.
"If a man lies with a woman during her sickness and uncovers her nakedness, he has exposed her flow, and she has uncovered the flow of her blood. Both of them shall be cut off from their people" (Leviticus 20:18).
In case you think this was a slight against women, men had equivalent laws. They became unclean for a day each time they ejaculated semen.
"If any man has an emission of semen, then he shall wash all his body in water, and be unclean until evening. And any garment and any leather on which there is semen, it shall be washed with water, and be unclean until evening. Also, when a woman lies with a man, and there is an emission of semen, they shall bathe in water, and be unclean until evening" (Leviticus 15:16-18).
The laws of uncleanness was to teach the Israelites about the nature of sin. The point of having some things unclean which cannot be avoided is to emphasize the fact that everyone sins (Romans 3:9, 23). Now that we are under the New Law of Christ, we no longer have laws of uncleanness, but as many people noted the laws of uncleanness did have a beneficial side-effect. Today we realize that they would significantly cut down on the spread of disease -- especially in a society that didn't understand about germs.