Romans 2:13-15

13For it is not the hearers of the law who are righteous before God, but the doers of the law who will be justified.

14For when Gentiles, who do not have the law, by nature do what the law requires, they are a law to themselves, even though they do not have the law.

15They show that the work of the law is written on their hearts, while their conscience also bears witness, and their conflicting thoughts accuse or even excuse them