We a have separate page about the narrations of Mutta'a (temporary marriage) that Umar bin Khattab banned Mutta'a. Please read more narrations in Sahih Muslim about Umar bin Khattab.
Please read all three narrations of Sahi Muslim.
Another Narration
Another Narration
These narrations prove that Umar bin Khattab changed the Quranic law of divorce (the one which was approved by the Sunnah of holy Prophet). It is more interesting thing that 4 Sunni schools of thought accept Umar's law and not the Quranic law.
We can see how many Muslim families suffered around the world over centuries and until the Day of Judgment. We can also see that Islam became a joke for other world that if someone says divorce three times to his wife, the wife get divorced.
Shia Muslims donot follow any change made by Umar bin Khattab. Shias are strict with this Islamic rule that anything which Prophet Mohammad (pbuh) allowed no one can change it and anything which Prophet (pbuh) disallowed no one can allow it!