Sayyiduna Ibn Umar (may Allah be pleased with them both) was asked about mut'ah (temporary marriage), and he said: It is forbidden. It was said: Ibn Abbas (may Allah be pleased with them both) sees no harm in it. So he said: "Listen! By Allah, Ibn Abbas knows well that the Messenger of Allah (peace and blessings be upon him) forbade it on the day of Hunayn, and we were not fornicators."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 13088