Final answer:
Jeremiah 31, especially verses 31-34, speaks of God establishing a New Covenant with His people, writing His laws on their hearts in the time of eschatological salvation.
Step-by-step explanation:
The chapter of Jeremiah that talks about what God would do in the hearts of His people in the time of eschatological (post-exilic) salvation is Jeremiah 31, particularly verses 31-34. This passage is known as the New Covenant, where God promises that He will put His law within the people and write it on their hearts. The promise indicates a deep, transformative change in the relationship between God and His people, where obedience to God's law will come from their inward conviction rather than through external regulations.