Charles Ellicott Commentary Deuteronomy 9:4

"Speak not thou in thy heart, after that Jehovah thy God hath thrust them out from before thee, saying, For my righteousness Jehovah hath brought me in to possess this land; whereas for the wickedness of these nations Jehovah doth drive them out from before thee." — Deuteronomy 9:4 (ASV)

But for the wickedness. —“Say not in your heart, ‘in my righteousness,’ when it is in consequence of their wickedness that Jehovah is dispossessing them from before you.”