Paul has told the reader what not to say. Now he asks what the righteousness of faith does say, so the reader will listen for the positive answer. The question turns attention from impossible journeys to a word that is already close. Barnes explains that the doctrine was nigh, that is, "it was easily obtained, embraced, and understood," and adds, "What is nigh us may be easily obtained."

Paul answers with Moses' words: "The word is nigh thee, even in thy mouth, and in thy heart" (Romans 10:8). Then he names it: "that is, the word of faith, which we preach." He spells out that word in Romans 10:9: "if thou shalt confess with thy mouth the Lord Jesus, and shalt believe in thine heart that God hath raised him from the dead, thou shalt be saved."

Moses had said, "But the word is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it" (Deuteronomy 30:14). Barnes notes this is "still a use of the language of Moses." Paul applies it to the gospel he and others preach. Gill calls "the word of faith" "the Gospel so called, because it contains doctrines which are to be believed," and says the apostles said no other things than what the prophets and Moses said.

The question leads to one of the clearest statements of the gospel in the Bible. God has not hidden the way to Himself. He has put it in a word that can be heard, believed in the heart, and confessed with the mouth (Romans 10:8-10). Matthew Henry (full commentary) says of this word, "there is no difficulty in understanding, believing, and owning it."

This nearness is for everyone: "For there is no difference between the Jew and the Greek: for the same Lord over all is rich unto all that call upon him" (Romans 10:12). The very next questions in the chapter ask how people will hear this near word unless someone preaches it (Romans 10:14-15).