Moses apparently had been praying to God for help so God uses this question to compel Moses to act. This rhetorical question can be translated as a statement. AT: "Do not call out to me any longer, Moses." (See: [[rc://en/ta/man/translate/figs-rquestion]])
Here "hearts" refers to the Egyptians themselves. Their stubborn attitude is spoken of as if their hearts were hard. See how you translated a similar phrase in [Exodus 9:12](../09/11.md). AT: "I will cause the Egyptians to became more defiant" (See: [[rc://en/ta/man/translate/figs-synecdoche]] and [[rc://en/ta/man/translate/figs-metaphor]])