Are the monthly amounts sent to return lost business capital considered usury?

If a person pays money as sadaqa (charity), and this was not stipulated for him, nor was he obligated to it in the agreement, but rather he donated it after the occurrence of a loss, then some scholars consider this action valid, contrary to the majority of jurists. Thus, volunteering to return the capital and donating to the partners monthly has a considered aspect, as long as it was not stipulated in the contract or at the commencement of the work. The Sharia (definition) Standards of the Accounting and Auditing Organization for Islamic Financial Institutions (AAOIFI) have stipulated that it is not permissible to stipulate absolute guarantee on the investment manager, nor is it permissible for him to undertake a guarantee after the contract. However, it is permissible for him to volunteer a guarantee out of his own free will when a loss occurs.