Romans 10:6-7 — But the righteousness which is of faith speaketh on this wise, Say not in thine heart, Who shall ascend into heaven? (that is, to bring Christ down from above:)
Or, Who shall descend into the deep? (that is, to bring up Christ again from the dead).
Quote from Deuteronomy 30:11-14 (taken from the Septuagint, with certain modifications and parenthetic explanations) — For this commandment which I command thee this day, it is not hidden from thee, neither is it far off. It is not in heaven, that thou shouldest say, Who shall go up for us to heaven, and bring it unto us, that we may hear it, and do it? Neither is it beyond the sea, that thou shouldest say, Who shall go over the sea for us, and bring it unto us, that we may hear it, and do it? But the word is very nigh unto thee, in thy mouth, and in thy heart, that thou mayest do it.
deep = abyss, Sheol, the region of the dead into which Christ went at His death. To think of a repetition of the death and resurrection of Christ would be to impute incompleteness to that which was accomplished once for all.
Man had nothing to do with the incarnation (verse 6) Man had nothing to do with the resurrection (verse 7). God did it all. Man cannot obtain righteousness by his own efforts, only by faith.
What Moses is saying is, in effect: “This law is not hidden from you; it is simple and plain. You don’t have to send to heaven to bring it down to your level, or send your philosophers across the sea to other lands to get their learned opinions about it. God has brought it down to you and as you receive it as His word you are saved. Is it not significant that immediately following these words in Deuteronomy 30:11-14, Moses says, “He is thy life.” — C.R. Stam, The Epistle of Paul to the Romans, Page 242.