What is the legal ruling regarding guaranteeing a loan with 5% interest for a commercial project, knowing that the guarantor is paying off a portion of the loan amount and is in need of money?

Borrowing with usury is one of the gravest sins and incurs the curse upon the one who consumes usury, the one who feeds it, its scribe, and its two witnesses. This also applies to anyone who completes the contract with a guarantee. The proof for this is the saying of the Messenger of Allah, peace and blessings be upon him: "The Messenger of Allah, peace and blessings be upon him, cursed the one who consumes usury, the one who feeds it, its scribe, and its two witnesses," and he said: "They are all equal [in sin]." So, if the guarantor will take a share of the usurious loan, then he combines direct involvement in usury with assisting others in it.