Abd al-Rahman bin A'idh (may Allah have mercy on him) narrates that a man asked Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him) about when the ritual bath (ghusl) becomes obligatory from intercourse, about praying in a single garment, and about what is permissible from a menstruating woman. Sayyiduna Mu'adh (may Allah be pleased with him) said: I asked the Messenger of Allah (peace and blessings be upon him) about that, and he (peace and blessings be upon him) said: "When the circumcised part passes beyond the circumcised part (they meet), the ritual bath becomes obligatory. As for prayer in a single garment, wrap yourself in it. And as for what is permissible from a menstruating woman, what is above the waist-wrapper is permissible, and refraining even from that is better."
Hadith Referenceالمعجم الكبير للطبراني / باب الميم / 17330