What does Genesis 32:9 mean?
According to Genesis 32:7, Jacob is terrified to hear that his estranged brother, Esau, is riding in his direction with 400 men. The language in the original Hebrew of verse 7 indicates a critical level of stress and fear. Jacob has good reason to believe Esau is coming to kill him. Twenty years prior, Jacob fled home to escape his brother's revenge (Genesis 27:41–45), after Jacob fooled their elderly father in order to steal Esau's blessing (Genesis 27:30–35).How will Jacob respond to this fear? Despite his reputation for selfish scheming, his attempt to "plan" here actually makes a lot of sense. In that sense, Jacob provides a good model for us. He takes what action he can, positioning his large company to save as many as possible (Genesis 32:7–8). Then Jacob prays.
God has told Jacob repeatedly that He would be with him. God has often demonstrated to Jacob His protection and blessing. Now Jacob demonstrates his faith in the God who protects and provides: he turns to God for help. That's what believers do. Jacob begins his prayer by addressing God as the God of Abraham and the God of Isaac, connecting to God's legacy of blessing for his fathers. Then Jacob refers to the Lord as the one who told him to return to his country and family and promised to do good to him.
In terms of his literal words, Jacob is reminding God of God's own promise. In effect, though, Jacob is reminding himself, both of God's history of goodness and the promise to continue to do good for him.