Romans 5:20-21:

Now the law came in to increase the trespass, but where sin increased, grace abounded all the more, so that, as sin reigned in death, grace also might reign through righteousness leading to eternal life through Jesus Christ our Lord.

Martyn Lloyd-Jones, Romans: Assurance (Banner of Truth, 1971), 299–300:

What grace has done is not merely to counteract exactly what sin has done. If grace had done just that, and that alone, it would still be something wonderful. If the effect of grace had merely been to wipe out, and to cancel, all that had happened on the other side, we should have had a theme for praising God sufficient to last us through all eternity.

But, says the Apostle, it is not an exact counterbalance; what I have on the right side does not exactly tally with what I have on the left. In fact there is no comparison; it is a superfluity, an abounding, and engulfing, it is an overflowing on the side of grace.

We must hold on to this truth at all costs and get it clear in our minds.