Reference: ‘Ishratun-Nisaa. wa Hill al-Khilaafaat az-Zowjiyyah – Page 54
Question: Is it obligatory for the married couple to take a ghusl after sexual intercourse, even if ejaculation did not occur?
Response: Yes. It is obligatory for them both to take a ghusl, even if ejaculation occurred or not. This is according to the hadeeth of Abu Hurayrah (radhi-yAllaahu ‘anhu) that the Prophet (sal-Allaahu ‘alayhi wa sallam) said:
«If he (the husband) sits amidst her (the wife) four parts, then had intercourse with her, then ghusl becomes obligatory», the authenticity of this hadeeth is agreed upon by both Imaam al-Bukhaaree and Imaam Muslim.
And in Imaam Muslim’s transmission it [additionally] states:
«…and even if he did not ejaculate».
And this [narration] is clear in the obligation of ghusl even without ejaculation, and this is little known to many people, so that which is obligatory is to beware and take heed of this.