when anyone sits between the four parts of a woman and the parts (of the male and female) which are circumscised join together, then bath becomes obligatory.
أَنَّ النَّبِيَّ ﷺ قَالَ إِذَا قَعَدَ بَيْنَ شُعَبِهَا الأَرْبَعِ وَأَلْزَقَ الْخِتَانَ بِالْخِتَانِ فَقَدْ وَجَبَ الْغُسْلُ