Surah Al-Baqarah · Ayah 222

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 Allāh has ordained for you. Indeed, Allāh loves those who are constantly repentant and loves those who purify themselves."

Translation: Saheeh International