What is the ruling on buying a commodity for cash, then selling it to a friend in installments and at a higher price after he has chosen it? And is Zakat obligatory on this money, and when, and how much?

The ruling on this transaction was previously explained, and it is permissible under certain conditions, resembling the Murabaha sale conducted by Islamic banks. As for the Zakat on the money owed by the party ordering the purchase, its ruling is the same as the ruling on Zakat for debts.