Sefer HaChinuch ספר החינוך

That we not give a hand between the borrower and the creditor with interest: To not be involved in an interest loan between the borrower and the creditor — meaning to say that we do not act as a guarantor for them and that we do not write a deed for them that has a mention of interest — as it is stated (Exodus 22:24), “you shall not place interest upon him.” And the explanation comes in Bava Metzia 75b that this negative commandment is stated about those involved in the matter, such as the guarantor, the witnesses and the scribe. And there it is said also that the creditor is included with them in this negative commandment, besides the other negative commandments that are specific to him. And the general principle of the matter is that which Abbaye said there that the creditor transgresses six negative commandments, the borrower two and those involved, one.

It is from the roots of this commandment [that it is] because the good God desired the settlement of His people which He chose. And therefore He commanded to remove the obstacle from their path, that one should not swallow up the wealth of his friend without his [even] feeling it, until he finds his house empty of all good. As this is the way of interest, and the matter is well-known, and that is why it is called, “bite (neshekh).” And in the avoidance of this matter by the guarantor, the scribe and the witnesses, [other] people will [also] avoid it. And the rest of its details are in [Bava] Metzia. (See Tur, Yoreh Deah 160.)

And [it] is practiced in every place and at all times by males and females. And one who transgresses it and becomes a scribe or a guarantor or a witness for the loan violates this negative commandment. But we do not administer lashes for it, since even the creditor does not [receive] lashes — as behold, it is given to returning. And [so] it is not right that these that come because of him be liable for lashes.