Hebrews 10:35

35.Cast not away, therefore, etc. He shows what especially makes us strong to persevere, even the retaining of confidence; for when that is lost, we lose the recompense set before us. It hence appears that confidence is the foundation of a godly and holy life. By mentioning reward, he diminishes nothing from the gratuitous promise of Salvation; for the faithful know that their labor is not vain in the Lord in such a way that they still rest on God’s mercy alone. But it has been often stated elsewhere how reward is not incompatible with the gratuitous imputation of righteousness.