Romans 6:16
Do you not know, that to whom you present yourselves servants unto obedience, ye are servants to whom you obey; whether of sin unto death, or obedience unto righteousness?
John 8:34
Jesus responded to them, Truly, truly, I say unto you, That every one doing sin is the slave of sin.
2 Peter 2:19
promising them liberty, they themselves being the slaves of corruption: for to whatsoever any one has been subordinated, to this he has become enslaved.
Matthew 6:24
No one is able to serve two masters: for he will hate the one, and love the other; or cleave to the one, and despise the other. You are not able to serve God and mammon.
Romans 6:12-13
Let not sin therefore reign in your mortal body that you should obey the lusts of it:
Romans 6:17
But thanks be unto God, that whereas ye were servants of sin, but you have obeyed from the heart the type of teaching into which ye were delivered:
Romans 6:19-23
I speak after the manner of a man on account of the weakness of your carnality. For as ye presented your members as servants unto impurity and lawlessness pursuant to lawlessness, so now present your members servants unto righteousness pursuant to sanctification.