The Mekhilta catalogs the multiple transgressions committed by someone who lends money at interest. From the Torah's various prohibitions against usury, the rabbis identified five separate violations in a single act of lending at interest.
"You shall not give" — the lender who advances money at interest violates this. "You shall not take" — the lender who collects interest violates this. "You shall not impose interest upon him" — the lender violates this by structuring the loan with interest. "You shall not be as a creditor to him" — the lender violates this by pressing for collection of the interest. And (Leviticus 19:14): "You shall not place a stumbling block before the blind man" — the lender violates this by tempting the borrower into a transaction that will harm him.
But the guilt does not stop with the lender and borrower. The guarantor, the witnesses, and the scribe who drafts the loan document all participate in the transgression. Each person who facilitates the interest-bearing loan shares in the guilt.
Rabbi Meir made one exception: he excluded the scribe from liability. In his view, the scribe merely records the agreement that others have made. He is a technician, not a participant in the substance of the transaction.
This comprehensive assignment of guilt transformed lending at interest from an individual sin into a collective one, implicating everyone in the chain from negotiation to documentation.