Deuteronomy 9 - God Gives Victory to the Humble and Punishes the Wicked
God promised to give seemingly impossible victory to the Israelites provided that they remained humble and never got conceited in their victories. God demands that same creator/created humble distinction between us all the time and it should be the mindset we are always checking ourselves on. God also reminds Israel that it is not because of their righteousness that God is giving them victory, but because of the wickedness of whom He is destroying. This is a direct parallel to the attitude we should have towards God's saving grace in Christ we have been gifted. We cannot look to our own righteousness as if we are the ones who earned it or deserve it, it's completely God's mercy and grace that provides itself.
God reminds Israel of their prior rebellions against Him as if they had forgotten. I personally love this because it gives advice against forgetting who we were before Christ. We should never forget the ways we rebel against God lest we end up tricking ourselves into thinking that we are above those rebellions today. I have heart something brought up in conversation before regarding "Holy Spirit Amnesia" that makes us forget the way we were before being transformed by faith in Christ. I don't believe that for a second because nowhere is this taught in scripture. It is actually quite the contrary. We are encouraged to remember our past failures as it gives us perspective on God's grace and forgiveness as well as shows us how far we have come. This is not to say lean on those past failures and torture ourselves over them, but to humbly remember that we are not righteous people at all. My favorite verse to remind me of this comes from Paul in his letter to the Romans.
"Wretched man that I am! Who will deliver me from this body of death? Thanks be to God through Jesus Christ our Lord! So then, I myself serve the law of God with my mind, but with my flesh I serve the law of sin."
Let us never forget that we fall short every single day and are in constant need of God's love and grace. Whenever we are not reminded, pride and self-righteousness tends to seep in and we must retain balance between self-righteousness and self-loathing as both lead to a false idea of God's attitude towards us.