Menstruation
They ask you about menstruation, say, 'It is a discomfort, so avoid intimacy during it. Do not approach them until they are purified. When they have cleansed themselves, then approach them as Allah has commanded.
2:222They question thee (O Muhammad) concerning menstruation. Say: It is an illness, so let women alone at such times and go not in unto them till they are cleansed. And when they have purified themselves, then go in unto them as Allah hath enjoined upon you. Truly Allah loveth those who turn unto Him, and loveth those who have a care for cleanness.