Abstract:This study aims at determining the position of Islamic law in the culture of Malay society in Jambi, Sumatera. The obvious facts in the previous studies about Islamic law and culture in Malay Sumatera is heavy emphasis on Minangkabau of West Sumatera with its matrilineal culture and traditionalist-modernist tension. In contrast, Jambi, which is adjacent to Minangkabau region, is starkly different. Jambi culture does not recognize matrilineal culture, except for Minangkabau people migrating to Jambi, nor experience such a tension. This is evidenced from interviews and library sources alike. Interviews were undertaken from several members of traditional leaders including some of the decendents of Jambi Malay Kingdom. As the result, even though there was a was among devotees of each of the laws, Islamic law (Syarak) and customary law in greater Malay Sumatera, the aphorism "Customary laws are based on religious laws; religious laws are based on the Holy Book" unites them, and becomes the living law that rules Muslim society in Jambi from the past until present day.

Buying and selling is mu'awadhah contract. The contract is carried out by the two parties, in which the first party and second party deliver the goods handed over in return, either in the form of money or goods. Where buying and selling online can streamline and streamline time so that one can make buying and selling with every person anywhere and anytime. All buying and selling over the internet is done without any face-to-face between his party, they base their buying and selling the above sense of trust with each other, so that the purchase agreement between the parties that occurred was done electronically. Based on the foundation of the rule Fiqih the buying and selling via online (internet) it is allowed, and valid, unless it is casuistry irregularities, manipulation, fraud and the like, it is also legal casuistry applied, which is forbidden. In the problem of buying and selling online, fiqh considers that the buying and selling in cyberspace allowed because mashlahah. Mashlahah is a benefit and harm refuse in order to maintain the goal of Personality. When e-commerce was seen as the withdrawal of trade in Islam, it may be analogous to that first seller is a merchant (Internet Service Provider or ISP), whereas buyers fondly called customer. Second, the object is to offer goods and services (such as the ordering as-salam) with a variety of information, profile, price list, seen pictures of goods, as well as the official company. And third, sighat (consent-qabul) performed with the payment gateway system or software support (authorities and monitors) for the acquirer, as well as useful for the onlin e service.