From Sahih Muslim (Hadith 781):
Zaid b. Khalid al-Jubani reported that he askad Uthman b. 'Affan:What is your opinion about the man who has sexual intercourse with his wife, but does not experience orgasm? Uthman said: He should perform ablution as he does for prayer, and wash his organ. 'Uthmin also said: I have heard it from the Messenger of Allah (ﷺ)
Reference: Muslim 781