Urwah (may Allah have mercy on him) said that Khawlah bint Hakim (may Allah be pleased with her) came to Umar bin al-Khattab (may Allah be pleased with him) and said: Rabi'ah bin Umayyah made a mut'ah marriage with a muwalladah woman (one born among the Arabs to non-Arab parents), and she became pregnant by him. So Umar (may Allah be pleased with him) came out of his house in alarm, dragging his cloak, and said: "This is mut'ah! Had I given a warning about it beforehand, I would have stoned him."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب النكاح / 14172