When a plot of ground is bought with money, it is that same money that, year after year, generates more money - that is, the income from the plot of ground itself.
Naturally, inactive coin is barren and fruitless; but the debtor doesn't leave it inactive. Thereafter, the debtor isn't deceived when he is invited to pay an interest, as that interest is part of the income he encashed from the money he had borrowed.
