Is financing from the Social Fund for Development (SFD) through Murabaha, where the Fund buys equipment and resells it to me in installments with a 5% interest, while holding the equipment as collateral, considered usury (riba)? And where does the flaw lie in this transaction?

As long as you will pay the fund 25% for it to complete the price of the equipment, this is a forbidden sale and loan. The correct approach is that you should not pay anything to the fund, or pay an amount as a serious down payment that the fund does not dispose of.

If this point is corrected, and the fund buys the equipment and it enters its possession and responsibility, then it sells it to you, there is no objection to that, and it is considered a legitimate Murabaha. A 5% profit for the fund is acceptable, and there is no problem in mortgaging the equipment and your utilizing it with the mortgagee's permission.

If the fund stipulates seizing the collateral upon default, this is not permissible. Rather, it has the right to sell it to take its due if the mortgagor permits it, or the ruler sells it if the mortgagor refuses to pay or sell the collateral.