"Heart" here is a metonym for a person's thoughts or intentions. AT: "with all honest intentions" or "with sincerity" (See: [[rc://en/ta/man/translate/figs-metonymy]])
Receiving what God has promised believers is spoken of as if it were inheriting property and wealth from a family member. (See: [[rc://en/ta/man/translate/figs-metaphor]])
The phrase "receive the penalty" means to be punished. AT: "anyone who does unrighteousness will be punished" or "God will punish anyone who does what is unrighteous"
The abstract noun "partiality" can be expressed with the adjective "partial." To be partial is to favor some people more than others. AT: "God is not partial" or "God judges everyone by the same standard" (See: [[rc://en/ta/man/translate/figs-abstractnouns]])