Do not enter into business dealings between lender and borrower using interest.
“Do not put interest upon him.” Shmot 22:24
Means do not be guarantor or witness for agreements between them.
The cost of interest may not be noticeable initially until the interest increases causing the loss of money.
The lender is included in this prohibition and additionally –not to lend to Jews at interest. (–54)
A middle man violates the commandment “before the blind do not place a stumbling block” (- 76)
In effect everywhere, in every time for men and women