As a result of foreplay (not proper intercourse), if either just husband or just wife reaches orgasm, while husband did not enter into wife and just external activities produced orgasm, who has to perform bath (Ghusl) just the one who reached orgasm or both?

All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah, and that Muhammad is His slave and Messenger.

Ghusl (ritual bath) does not become obligatory unless there is intercourse or ejaculation of sperm. The Prophet said: "When anyone sits amidst the four parts (of the woman) and the circumcised parts touch each other, a bath becomes obligatory (for both) even if he does not ejaculate." [Muslim]

Another narration reads: "It is with the seminal emission that Ghusl becomes obligatory.” [Muslim, Ahmad and An-Nassaa'i] This means that using water for Ghusl is obligatory only if the husband or the wife ejaculates, or when there is intercourse, in which case, both of them are obliged to perform Ghusl.

However, if there is no intercourse, it is only the partner who ejaculated who should perform Ghusl.

Allaah Knows best.