the Fatwa Department Research Committee - chaired by Sheikh `Abd al-Wahhâb al-Turayrî
The Prophet (peace be upon him) said: “Allah curses the one who consumes interest, the one who pays it, the one who draws up the contract, and the witnesses to the contract, then he said they are same (in sinfulness) ” [Sahîh Muslim]
This hadîth shows us that it is unlawful in Islamic Law to receive interest and to pay it. Both parties share in the sin of the transaction of interest.
However, there is an extremely important distinction between paying interest and receiving it. This distinction is that unlawful wealth is only acquired by the party that receives interest. The one who pays the interest shares in the sin of the transaction, but he is not stuck with unlawful wealth as a consequence of it.
When a person borrows money on interest, that person is not receiving unlawful income, but is engaging in an unlawful transaction.
The reason why the borrower who takes out an interest loan does not receive any unlawful money is that receiving a loan in and of itself is lawful. What is unlawful and sinful is his agreeing to the unlawful condition of paying back the loan with interest.
When the person pays the interest, the recipient of the interest – the lender – receives unlawful money. The party who pays the interest shares in the sin for the interest transaction, but he does not acquire unlawful income as a consequence.
Therefore, we cannot say that the one who pays interest is sinning as badly as the hadîth you mention and other hadîth describe, simply because those hadîth may be referring to the cumulative sins that come from consuming unlawful wealth, which only apply to those who consume interest, not to those who pay it.
And Allah knows best.
Source: Islam Today