Abd al-Rahman bin A'idh narrates: A man asked Sayyiduna Mu'adh bin Jabal (may Allah be pleased with him): What, in intercourse, makes the ritual bath (ghusl) obligatory? What is the ruling on praying in a single garment? And to what extent is contact with a menstruating woman permissible? Sayyiduna Mu'adh (may Allah be pleased with him) said: I asked the Prophet (peace and blessings be upon him) about this, and he (peace and blessings be upon him) said: "When the private part passes the private part, the ritual bath becomes obligatory. As for praying in a single garment, the Prophet (peace and blessings be upon him) wrapped it around himself crosswise (tawshih) and prayed. As for intimacy with a menstruating woman, contact with what is above the waist-wrapper is permissible, but keeping away even from that is more virtuous."
Al-Tabarani recorded it in al-Mu'jam al-Kabir. Abu Dawud recorded the part about the menstruating woman; among Abu Dawud's narrators is Baqiyyah bin al-Walid, who is da'if (weak) because of his tadlis (concealing defects in the chain). The chain of this report is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الطهارة / 1441