The Westminster Shorter Catechism (1648)

14 For when the Gentiles, which have not the law, do by nature the things contained in the law, these, having not the law, are a law unto themselves:

15 Which show the work of the law written in their hearts, their conscience also bearing witness, and their thoughts the mean while accusing or else excusing one another;)

5 For Moses describeth the righteousness which is of the law, That the man which doeth those things shall live by them.