Al Baqarah, 222 Ayah
2:222
وَيَسۡـَٔلُونَكَ عَنِ ٱلۡمَحِيضِۖ قُلۡ هُوَ أَذٗى فَٱعۡتَزِلُواْ ٱلنِّسَآءَ فِي ٱلۡمَحِيضِ وَلَا تَقۡرَبُوهُنَّ حَتَّىٰ يَطۡهُرۡنَۖ فَإِذَا تَطَهَّرۡنَ فَأۡتُوهُنَّ مِنۡ حَيۡثُ أَمَرَكُمُ ٱللَّهُۚ إِنَّ ٱللَّهَ يُحِبُّ ٱلتَّوَّٰبِينَ وَيُحِبُّ ٱلۡمُتَطَهِّرِينَ ٢٢٢
Wa Yas'alūnaka `Ani Al-Maĥīđi ۖ Qul Huwa 'Adháan Fā`tazilū An-Nisā' Fī Al-Maĥīđi ۖ Wa Lā Taqrabūhunna Ĥattá Yaţhurna ۖ Fa'idhā Taţahharna Fa'tūhunna Min Ĥaythu 'Amarakumu Al-Lahu ۚ 'Inna Al-Laha Yuĥibbu At-Tawwābīna Wa Yuĥibbu Al-Mutaţahhirīna
And they ask you about menstruation. Say, "It is harm, so keep away from wives during menstruation. And do not approach them until they are pure. And when they have purified themselves, then come to them from where Allah has ordained for you. Indeed, Allah loves those who are constantly repentant and loves those who purify themselves."