If he sits between her four limbs and exerts himself, the ritual bath becomes obligatory

Explanation of the hadith

If a man sits between a woman's four limbs, i.e. her arms and legs, and he inserts his male organ into her vagina, then it is obligatory on both of them to take a ritual bath in order to remove the major ritual impurity even if no semen is discharged. Penetration on its own necessitates ritual bath.