The implicit answer to this question is, "No one can say that." This rhetorical question can be written as a statement. Alternate translation: "No one can say that his heart is clean and that he is free from sin" (See: [[rc://en/ta/man/translate/figs-rquestion]])
A person who God considers spiritually acceptable is spoken of as if the person where physically clean. (See: [[rc://en/ta/man/translate/figs-metaphor]])