Quran 2, Al-Baqara (The Cow) ⓘ

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.

وَيَسْأَلُونَكَ عَنِ الْمَحِيضِ قُلْ هُوَ أَذًى فَاعْتَزِلُوا النِّسَاءَ فِي الْمَحِيضِ وَلَا تَقْرَبُوهُنَّ حَتَّى يَطْهُرْنَ فَإِذَا تَطَهَّرْنَ فَأْتُوهُنَّ مِنْ حَيْثُ أَمَرَكُمُ اللَّهُ إِنَّ اللَّهَ يُحِبُّ التَّوَّابِينَ وَيُحِبُّ الْمُتَطَهِّرِينَ