Romans 10:6

“But the--justifying righteousness which is of faith speaketh on this wise--"speaketh thus"--its language or import is to this effect (quoting in substance Deu 30:13-14). Say not in thine heart, Who shall ascend into heaven? that is, to bring Christ down, &c.--that is, "Ye have not to sigh over the impossibility of attaining to justification; as if one should say, oh! if I could but get someone to mount up to heaven and fetch me down Christ, there might be some hope, but since that cannot be, mine is a desperate case."”

“But the righteousness which is of faith - It is observable here that Paul does not affirm that Moses describes any where the righteousness by faith, or the effect of the scheme of justification by faith. His object was different, to give the Law, and state its demands and rewards. Yet though he had not formally described the plan of justification by faith, yet he had used language which would fitly express that plan. The scheme of justification by faith is here personified, as if it were living and describing its own effects and nature. One describing it would say, Or the plan itself speaks in this manner. The words here quoted are taken from Deuteronomy 30:11-14. The original meaning of the…”

“But the righteousness which is by faith - The method of becoming righteous by believing. Speaketh a very different language, and may be considered as expressing itself thus: (to accommodate to our present subject the words which Moses spake, touching the plainness of his law:) Say not in thy heart, Who shall ascend into heaven, as if it were to bring Christ down: or, Who shall descend into the grave, as if it were to bring him again from the dead - Do not imagine that these things are to be done now, in order to procure thy pardon and salvation. Deu 30:14. Romans 10:8”

“10:6-8 Here Paul quotes three phrases from Deut 30:12-14 dealing with the law, and he applies them to the Good News about Christ. We do not need to go up to heaven to find Christ (and thus to be made right with God), because God has already brought him down to earth as a man. Nor do we need to go down to the place of the dead to find Christ, because God has already raised him from the dead. To find Christ, we must simply believe in the message that is close at hand.”

“righteousness: Rom 3:22, Rom 3:25, Rom 4:13, Rom 9:31; Phi 3:9; Heb 11:7 Say not: The Apostle here takes the general sentiment, and expresses it in his own language; beautifully accommodating what Moses says of the law to his present purpose. Deu 30:11-14; Pro 30:4 to bring: Joh 3:12, Joh 3:13, Joh 6:33, Joh 6:38, Joh 6:50, Joh 6:51, Joh 6:58; Eph 4:8-10; Heb 1:3 Romans 10:7”