Is mut'ah marriage fornication, or is it merely unlawful, and what is the opinion of the four imams on this issue?

Nikah al-Mut'ah (temporary marriage) is forbidden by consensus (ijma'). The Imams have narrated the consensus of scholars on its prohibition, with the exception of the Rafidah (Shiites). The majority of jurists hold that nikah al-mut'ah is not zina (fornication/adultery) and does not necessitate the prescribed punishment (hadd), but rather a severe discretionary punishment (ta'zir). This is due to the presence of a شبهة العقد (semblance of a contract) in it, and the establishment of some marital rulings for it, such as the mahr (dowry), the establishment of lineage, and the prohibition of marital affinity. However, the Shafi'is, contrary to the sounder view, and a weak opinion among the Malikis, held that it is zina and necessitates the prescribed punishment if the contracting parties were aware of its prohibition. Some jurists differentiate between cases where the contract was made with a guardian (wali) and two witnesses, in which case no hadd is applied, and cases where it was only between the man and the woman, in which case the hadd becomes obligatory.