Narrated Abu Huraira (rad):

Allah’s Messenger (ﷺ) said that, “If one of you sits between her legs (of a woman) and penetrates her, Ghusl (bath) is obligatory.” [Agreed upon].

وَعَنْ أَبِي هُرَيْرَةَ ‏- رضى الله عنه ‏- قَالَ: قَالَ رَسُولُ اَللَّهِ ‏- صلى الله عليه وسلم ‏-{ إِذَا جَلَسَ بَيْنَ شُعَبِهَا اَلْأَرْبَعِ, ثُمَّ جَهَدَهَا, فَقَدْ وَجَبَ اَلْغُسْلُ } مُتَّفَقٌ عَلَيْه ِ [1]‏ .‏