comparative study of agreement on transactions in islamic jurisprudence and iranian law

to investigate the letter of promise in principles and documentation of jurisprudence, we should go unto resources required people to fulfill its obligations and treaties. quranic explanation such  as and prophetic narrations have been applied to all contracts and conditions and required muslims in each age and time, to be loyal to all their obligations and treaties (that are not inconsistent to the general principles of religious law).  in iranian legal system, contracts had been in two forms including: certain contracts and uncertain contracts. the letter of promise have been included  article 10 of the civil code and is binding document  in accordance with article 10 of the civil code that says:" private contracts are penetrating towards those who have signed it if it is not against the law". there are many signs to the necessity of letters of promise obligations in verses, narrations and legal articles, so that this document, in addition to credibility is irrevocable if it has been set correctly. and pledged cannot deny these obligations with his unilateral will   and without compromising the obligee and refuses to do it.