It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said:
"When (a man) sits between the four parts of his wife's body and exerts himself, then Ghusl becomes obligatory."Abu 'Abdur-Rahman said: "This is a mistake what is correct is; 'Ash'ath from Al-Hasan, from Abu Hurairah.' An-Nadr bin Shumail, and others, reported the Hadith from Shu'bah just as Khalid reported it." (ES)
English reference (ES): Vol. 1, Book 1, Hadith 192 (ES)
Arabic reference (ES): Book 1, Hadith 193 (ES)