Temporary marriage, or mut'a, is the practice of entering into a marriage with a time limit: the couple is married only for a night, or a week, or whatever time period their agreement specifies. So in other words, it is prostitution under the guise of morality. Temporary wives are found in large numbers in seminary towns where young clerics-in-training are away from home and lonely.
This is a Shi'ite concept that mainstream Sunnis ostensibly reject; the Shi'ites point out that Muhammad allowed it, while the Sunnis maintain that he later abolished the practice. Shi'ites also justify it by reference to Qur'an 4:24, which says: "And those of whom ye seek content (by marrying them), give unto them their portions as a duty. And there is no sin for you in what ye do by mutual agreement after the duty (hath been done)." They see in that reference to "what ye do by mutual agreement" the allowance of a time limit.
It is not unheard-of among Sunnis, as you can see here.
"Temporary marriages with Indonesian women on rise," by P.K. Abdul Ghafour for Arab News, April 18 (thanks to Jose):
JEDDAH: A large number of Saudis are engaging in temporary marriages with Indonesian women with the intention of divorcing them.
“Such marriages are likely to increase if Islamic scholars fail to give a clear ruling prohibiting them,” said Khaled Al-Arrak, director of Saudi affairs at the Saudi Embassy in Jakarta.
He said most Saudis were engaged in such marriages without realizing their consequences. “Some poor Indonesians marry off their girls to Saudis hoping it would put an end to their poverty and miseries. If the Council of Senior Islamic Scholars does not ban this type of marriages, things will go out of control,” Al-Arrak warned.
There are so many offices in Indonesia that facilitate such marriages, Al-Watan Arabic daily said. The marriage takes place in the presence of witnesses and a man posing as the father of the bride.
These women do not know that their marriages would end within a few days and that they would have to bear children of people who would abandon them.
Last year, the Saudi Embassy in Jakarta received 82 calls regarding children of Saudis who had married Indonesian women and then abandoned them. “We have received 18 such calls from abandoned Indonesian wives of Saudis and their children this year so far,” Al-Arrak said.
The Saudi Embassy official said that the cases registered with the embassy accounted for only 20 percent of such marriages that have actually taken place....