Refuting those who permit investment riba, who claim that riba is permissible if it does not involve injustice.

The Shaykh : I say this hadith breaks the backs of those who say that riba is lawful if it does not involve injustice. How is that? Yes, brother.
The student: Because Bilal bought by mutual agreement...

The Shaykh : That is what does not involve injustice. Good.
The student: ...

The Shaykh : Well done. Rest now. That is fine. No, mutual agreement, and also the value is the same. There is no injustice in this, because let us suppose the good sa' is worth ten, and the two sa' of the inferior one are worth how much? Ten. So equality is achieved between them in value, and there is mutual agreement between the contracting parties. This does not involve injustice. And yet the Prophet (peace and blessings be upon him) was pained by this transaction and said that it is the very essence of riba. As for those who were confused, they said that riba is not forbidden unless it involves injustice. They were confused by the saying of Allah the Exalted: They said this is evidence that riba is lawful if it does not involve injustice. And they built upon this that investment riba is permissible and exploitative riba is forbidden. It is said to them: Where did you get this distinction from? The hadith of Abu Sa'id that we just read indicates that the operative cause is not injustice. Injustice may be present in some forms of riba, but the operative cause is that the Lawgiver prohibited excess when a type of ribawi money is sold for its own type. This is the operative cause. And our position regarding such commands and prohibitions is to say what? We heard and we obeyed.