He asked the Messenger of Allah ﷺ about a man who draws close to his wife and emits prostatic fluid. He said, "When any of you experiences that, let him wash his private part," meaning rinse it, "and perform ablution as he does for prayer."
حدثنا عثمان بن عمر أنبأنا مالك عن سالم أبي النضر عن سليمان بن يسار
أنه سأل رسول الله ﷺ عن الرجل يدنو من امرأته فيمذي قال إذا وجد ذلك أحد فلينضح فرجه قال يعني يغسله وليتوضأ وضوءه للصلاة
Its chain of transmission is sahih, it was mentioned previously at 23698.