What is the ruling on mortgaging a plot of land from a neighbor in exchange for a sum of money to utilize it for agriculture, then returning the money and retrieving one's land, given the questioner's fear of the semblance of usury? And what is the ruling on the questioner working on this land and helping his family with it?

The aforementioned amount (40,000) is a loan. The mortgagee (the lender) benefits from the mortgaged land in exchange for this loan, and this is clear usury (riba), because the mortgagee's benefiting from the collateral in exchange for the loan is usury. This is different from a situation where the collateral is for a sale, in which case it is permissible provided the manner and duration of benefiting are specified. The questioner's situation is further complicated by the unknown term of the loan or the mortgage. His family's benefiting from the land is usury, so he should not assist them; rather, he should advise them to correct the situation by taking the land on lease (rent) or through sharecropping.