Ibrahim narrates: Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) was asked about a man who has intercourse with his wife but does not ejaculate. He said: "As for me, when I reach that point with a woman, I take a ritual bath (ghusl)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9221