Is it permissible to refinance an existing Murabaha with Arab Bank to increase the amount for completing a house, and is it permissible to take financing from the same bank?

It is permissible to refinance, provided it is independent of the first financing, meaning there should be no agreement to repay the first debt with the second. As for obtaining financing from the Arab Bank, its forms are as follows:

1. Stock financing: Permissible if the stocks are owned by the bank, permissible [to trade], the customer does not sell them except after taking possession, and there is no late payment penalty.

2. Commodity financing (e.g., rice and iron): Permissible if the bank genuinely purchases the commodity and then sells it to the customer in installments, and the customer takes possession of it before selling it to a third party for cash at a lower price, and there is no late payment penalty. However, if neither the bank nor the customer takes possession of the commodity, and the operation is merely authorizing the bank to sell it without possession, then it is forbidden and is called organized Tawarruq (monetization) by banks.