Moses
Deuteronomy 9:4ESV·traditional attribution

“Do not say in your heart, after the LORD your God has thrust them out before you, ‘It is because of my righteousness that the LORD has brought me in to possess this land,’ whereas it is because of the wickedness of these nations that the LORD is driving them out before you.

John Calvin Reformed @genevareformer

4. Speak not thou in thine heart. He now more plainly warns the people not to exalt themselves in proud and foolish boasting. If they had not been naturally so depraved and malignant, it would have been sufficient to point out God’s grace in a single word; but he could not induce them to gratitude except by correcting and destroying their pride.

Matthew Henry Presbyterian @wholebiblehenry

The call to attention (Deu 9:1), Hear, O Israel, intimates that this was a new discourse, delivered at some distance of time after the former, probably the next sabbath day. I. Moses represents to the people the formidable strength of the enemies which they were now to encounter, Deu 9:1.

Commenting on Deuteronomy 9:1-6

John Gill Reformed Baptist @doctorgill

Speak not thou in thine heart,.... Never once think within thyself, or give way to such a vain imagination, and please thyself with it: after that the Lord thy God hath cast them out from before thee; to make way for the Israelites, and put them into the possession of their land; which is to be ascribed not to them, but to the Lord: saying...