Al-Kāfi - Volume 3 > Reason Necessitating Ghusl (bath) for Men and Women
Hadith #7

7ـ الْحُسَيْنُ بْنُ مُحَمَّدٍ عَنْ عَبْدِ الله بْنِ عَامِرٍ عَنْ عَلِيِّ بْنِ مَهْزِيَارَ عَنِ الْحُسَيْنِ بْنِ سَعِيدٍ عَنْ مُحَمَّدِ بْنِ الْفُضَيْلِ قَالَ سَأَلْتُ أَبَا الْحَسَنِ (عَلَيْهِ الْسَّلام) عَنِ الْمَرْأَةِ تُعَانِقُ زَوْجَهَا مِنْ خَلْفِهِ فَتَحَرَّكُ عَلَى ظَهْرِهِ فَتَأْتِيهَا الشَّهْوَةُ فَتُنْزِلُ الْمَاءَ عَلَيْهَا الْغُسْلُ أَوْ لاَ يَجِبُ عَلَيْهَا الْغُسْلُ قَالَ إِذَا جَاءَتْهَا الشَّهْوَةُ فَأَنْزَلَتِ الْمَاءَ وَجَبَ عَلَيْهِ الْغُسْلُ.

7. Al-Husayn ibn Muhammad has narrated from ‘Abd Allah ibn ‘Amir from Ali ibn Mahziyar from al-Husayn ibn Sa‘id from Muhammad ibn al-Fudayl who has said the following: “I once asked abu al-Hassan, ‘Alayhi al-Salam, about the case of a woman who hugs her husband from his backside. She moves and experiences orgasm and discharge, is Ghusl (bath) necessary on her? He (the Imam) said, ‘If she experiences orgasm and discharge, Ghusl (bath) becomes necessary.”’