Liaison office of Grand Ayatullah Sayyid Ali Al Sistani (L.M.H.L) in London, Europe, North and South America.
Ruling 2382. To conclude a marriage contract, whether that be for a permanent marriage or a temporary one, a formula (ṣīghah) must be said; the mere consent of the man and the woman is not sufficient, nor is a written contract, based on obligatory precaution (al-iḥtiyāṭ al-wājib). The man and the woman can say the formula themselves, or they can appoint an agent (wakīl) to say it on their behalf.
Ruling 2383. The agent does not have to be a man; a woman can also be an agent on behalf of a party to say the formula of the marriage contract.
Ruling 2384. As long as the man and the woman are not confident (i.e. they do not have iṭmiʾnān) that their agent has said the formula, they cannot consider themselves legally married. Merely supposing (i.e. having ẓann) that the agent has said the formula does not suffice. In fact, if an agent says that he has said the formula but they do not have confidence in what he says, the obligatory precaution is that they must not heed what he says.
Ruling 2385. If a woman appoints an agent to marry her to a man for ten days, for example, but she does not specify a starting date for those ten days, the agent can marry her to the man for ten days starting from whenever he likes. However, if it is known that the woman has intended a specific date or time, the agent must say the formula according to her intention (qaṣd).
Ruling 2386. One individual can be an agent for both parties to say the formula of the marriage contract, be it temporary or permanent. A man can be an agent for the woman to marry her to himself, both in a temporary marriage and a permanent one. However, the recommended precaution (al-iḥtiyāṭ al-mustaḥabb) is that the formula should be said by two individuals.