Acquaintance with this covenant is of the greatest importance, for whoever errs here or denies the existence of the covenant of works will not understand the covenant of grace, and will readily err concerning the mediatorship of the Lord Jesus. Such a person will very readily deny that Christ by His active obedience has merited a right to eternal life for the elect. This is to be observed with several parties who, because they err concerning the covenant of grace, also deny the covenant of works. Conversely, whoever denies the covenant of works, must rightly be suspected to be in error concerning the covenant of grace as well.
Wilhelmus à Brakel (1635—1711), The Christian’s Reasonable Service, 1.355.