Rashi on Deuteronomy 7:8/רש"י על דברים ז׳:ח׳

1כי מאהבת — Here, however, you have the word כי used in the sense of “but": NOT ON ACCOUNT THAT YE WERE MORE NUMEROUS … DID GOD DELIGHT IN YOU … BUT ON ACCOUNT OF THE LORD'S LOVE TO YOU.

2ומשמרו את השבועה means, on account of His keeping the oath.