"Do not impose interest upon him": What is the intent of this? (Leviticus 25:37) "Your money you shall not give him on interest" is an exhortation to the lender. Whence do we derive (the same for) the borrower? From (Ibid. 36) "You shall not take from him interest."
The Torah's Prohibition Against Charging Interest Is One of the Most
Mekhilta Tractate Kaspa 1:7