Paul uses this question to call attention to what he is about to say, not to receive an answer. He speaks of the Scriptures as if they were alive and could talk. Alternate translation: "For this is what is in the scripture:" (See: [[rc://en/ta/man/translate/figs-rquestion]] and [[rc://en/ta/man/translate/figs-personification]])
You can translate this in an active form. Alternate translation: "God considered Abraham to be a righteous person because he believed" (See: [[rc://en/ta/man/translate/figs-activepassive]])