Is exchanging 50 Moroccan dirhams for 49 dirhams, with the remaining dirham being forgiven, considered usury, especially since the intention was not profit, and if so, what should be done?

For the exchange of currencies of the same type, parity and immediate possession in the مجلس (session/meeting) are required, based on the saying of the Prophet, peace and blessings be upon him: "Gold for gold... like for like, equal for equal, hand to hand." Monetary currencies have the rulings of gold and silver regarding usury (riba) and zakat. If the currencies differ, then disparity is permissible, but delaying possession is forbidden.

As for exchanging an amount with a gift of the excess, such as exchanging 49 dirhams for 49 and gifting the remaining dirham, this is permissible according to the majority of scholars if it is not a condition, because the basic principle regarding contracts and conditions is validity, unless legislated otherwise or forbidden.