What is the ruling on a borrower insisting on linking the repayment of his debt to the extent of money recovered from the company in which both parties invested?

Your friend must repay what he borrowed from you if he is able to do so. Otherwise, you must grant him a reprieve until he becomes capable. It is not permissible for him to procrastinate or delay payment, because the procrastination of the rich is an injustice. Rights will be fulfilled, and whoever has good intentions in fulfilling people's rights will be aided by Allah. As for whoever dies owing people rights, he will be held accountable for them on the Day of Judgment through good deeds and sins.