Romans 6:18

Being then made free from sin - Ελευθερωθεντες is a term that refers to the manumission of a slave. They were redeemed from the slavery of sin, and became the servants of righteousness. Here is another prosopopoeia: both sin and righteousness are personified: sin can enjoin no good and profitable work; righteousness can require none that is unjust or injurious.