Here "righteousness" is described as a person who can speak. Alternate translation: "But Moses writes this about how faith makes a person right before God" (See: [[rc://en/ta/man/translate/figs-personification]])
Moses was addressing the people as if he were speaking to only one person. Here "heart" is a metonym for a person's mind or inner being. Alternate translation: "Do not say to yourself" (See: [[rc://en/ta/man/translate/figs-you]] and [[rc://en/ta/man/translate/figs-metonymy]])
Moses uses a question to teach his audience. His previous instruction of, "Do not say" requires a negative answer to this question. You can translate this question as a statement. Alternate translation: "No one is able to go up to heaven" (See: [[rc://en/ta/man/translate/figs-rquestion]])