Is it Islamically permissible to sell a plot of land acquired from the municipality, and is it permissible to sell it to another buyer before taking full possession of it, and what is the ruling on the sale if it involves an element of gharar (excessive uncertainty) after more than ten years have passed?

If the ownership of the land was transferred to you with knowledge of its characteristics, then the sale is valid and enforceable, even if by installments. However, if you bought the land while ignorant of its area or location, then the sale is void, and the price must be returned to the buyer and the commodity to the seller. If it is impossible to return the commodity to the buyer, then he owns it and pays the remaining installments. Your sale of the land to another person is void if your first sale was void. However, if your first sale was valid and the second buyer was aware of what he purchased, then the sale is valid. And if the second buyer was not aware of what he purchased, then the sale is void.