Deuteronomy 7:9

9 Understand, therefore, that the LORD your God is indeed God. He is the faithful God who keeps his covenant for a thousand generations and lavishes his unfailing love on those who love him and obey his commands.

Deuteronomy 7:9 Meaning and Commentary

Ver. 9 Know therefore that the Lord thy God, he is God
The only true and living God, and not the idols of the Gentiles, who are false and lifeless ones, and therefore not the proper objects of adoration:

the faithful God, which keepeth covenant and mercy;
as appeared by fulfilling the promise made to their fathers, in bringing them out of Egypt, and now them to the borders of the land of Canaan given them for an inheritance:

with them that love him, and keep his commandments, to a thousand
generations;
see ( Exodus 20:6 ) which are not the causes or conditions of his covenant and mercy, nor of his keeping them, but descriptive of the persons that enjoy the benefit thereof.

Deuteronomy 7:9 In-Context

7 “The LORD did not set his heart on you and choose you because you were more numerous than other nations, for you were the smallest of all nations!
8 Rather, it was simply that the LORD loves you, and he was keeping the oath he had sworn to your ancestors. That is why the LORD rescued you with such a strong hand from your slavery and from the oppressive hand of Pharaoh, king of Egypt.
9 Understand, therefore, that the LORD your God is indeed God. He is the faithful God who keeps his covenant for a thousand generations and lavishes his unfailing love on those who love him and obey his commands.
10 But he does not hesitate to punish and destroy those who reject him.
11 Therefore, you must obey all these commands, decrees, and regulations I am giving you today.