What is the ruling on lending money to a person so that he may pay off the remainder of his debts to the bank, in order for him to own a house that he will then sell to me?

If the lender stipulates to the borrower the sale of a house or other property within the loan contract, this is not permissible. This is due to the prohibition by the Prophet (peace be upon him) of "a sale and a loan," and because it is the stipulation of one contract within another. Generally, it is not permissible for the lender to stipulate in the loan contract a condition that brings benefit to himself. Rather, any conditions accompanying the loan must be solely for the benefit of the borrower. Any condition that leads to a benefit for someone other than the borrower invalidates the loan.