Deuteronomy 7:9-12

9Know therefore that the Lord thy God, he is God, the faithful God, which keepeth covenant and mercy with them that love him and keep his commandments to a thousand generations; 10And repayeth them that hate him to their face, to destroy them: he will not be slack to him that hateth him, he will repay him to his face. 11Thou shalt therefore keep the commandments, and the statutes, and the judgments, which I command thee this day, to do them.

12Wherefore it shall come to pass, if ye hearken to these judgments, and keep, and do them, that the Lord thy God shall keep unto thee the covenant and the mercy which he sware unto thy fathers:1