The Study of Attribution of Validity and Irrevocability of Sale by Conduct to Sheikh Mofid

One of the current transactions between people is sale by conduct so that its illegitimacy causes problems and dilemma in Islamic society because most of the dealings between people are done by conduct. Although legislature has noticed this necessity and has incorporated and accepted legitimacy of sale by conduct in article 338 of civil law, jurisconsults have expressed numerous theories in the nature of sale by conduct and all of them are in contrast with this article of civil law. The only conforming theory with this article is the theory of Sheikh Mofid in validity and irrevocability of sale by conduct. But the problem of this theory is that well- known jurisconsults have expressed doubts and denied it and consequently they have interpreted the sale by conduct to invalid sale or permissiveness in restrictive and unrestrictive use or unstable transfer of property and they have created four theories against the Sheikh Mofid theory. This article is an attempt to prove the attribution of validity and irrevocability of sale by conduct to Sheikh Mofid and make clear the reasons of this theory with the method of using library and inferential analysis of juridical texts and sources.