Adam Clarke on Romans 6:14

Sin shall not have dominion over you - God delivers you from it; and if you again become subject to it, it will be the effect of your own choice or negligence.

Ye are not under the law - That law which exacts obedience, without giving power to obey; that condemns every transgression and every unholy thought without providing for the extirpation of evil or the pardon of sin.

But under grace - Ye are under the merciful and beneficent dispensation of the Gospel, that, although it requires the strictest conformity to the will of God, affords sufficient power to be thus conformed; and, in the death of Christ, has provided pardon for all that is past, and grace to help in every time of need.