Customized Murabahah is one of the most important types of Murabahah sale, which is widely used as one of the financing tools in Iran's banking system. The main question in this article is the Shariah ruling of this transaction and its limitation for bank financing. The method of this research is descriptive analysis and the data collection method is library. Based on the review of traditions related to custom-made Murabahah, the prohibition of creating any obligation towards the parties to perform Murabahah sale before the purchase of goods and the necessity of discretion for them have been used. The point of this prohibition is based on numerous evidences, to create restrictions for the use of this contract and to prevent its promotion as a common trick of usury. The actual adherence to this rule and other restrictions of custom murabaha as a type of sale, causes its inadequacy for bank financing and the inappropriate expansion of this contract in the banking system causes the expansion of formal contracts in banking facilities.