Just to show that you are accusing someone of proof texting (something only a fool would accuse Calvin of) by proof texting his words I present the following from which only one sentence is taken from in his commentary on Romans 10.
"5. For Moses, etc. To render it evident how much at variance is the righteousness of faith and that of works, he now compares them; for by comparison the opposition between contrary things appears more clear. But he refers not now to the oracles of the Prophets, but to the testimony of Moses, and for this reason, -- that the Jews might understand that the law was not given by Moses in order to detain them in a dependence on works, but, on the contrary, to lead them to Christ. He might have indeed referred to the Prophets as witnesses; but still this doubt must have remained, "How was it that the law prescribed another rule of righteousness?" He then removes this, and in the best manner, when by the teaching of the law itself he confirms the righteousness of faith.
For Moses describes, etc. Paul has graphei writes; which is used for a verb which means to describe, by taking away a part of it [epigraphei.] The passage is taken from
Leviticus 18:5, where the Lord promises eternal life to those who would keep his law; for in this sense, as you see, Paul has taken the passage, and not only of temporal life, as some think. Paul indeed thus reasons, -- "Since no man can attain the righteousness prescribed in the law, except he fulfills strictly every part of it, and since of this perfection all men have always come far short, it is in vain for any one to strive in this way for salvation: Israel then were very foolish, who expected to attain the righteousness of the law, from which we are all excluded." See how from the promise itself he proves, that it can avail us nothing, and for this reason, because the condition is impossible. What a futile device it is then to allege legal promises, in order to establish the righteousness of the law! For with these an unavoidable curse comes to us; so far is it, that salvation should thence proceed. The more detestable on this account is the stupidity of the Papists, who think it enough to prove merits by adducing bare promises. "It is not in vain," they say, "that God has promised life to his servants." But at the same time they see not that it has been promised, in order that a consciousness of their own transgressions may strike all with the fear of death, and that being thus constrained by their own deficiency, they may learn to flee to Christ.
This is specifically dealing with Romans 10:5
For Moses describeth the righteousness which is of the law, that the man which doeth those things shall live by them. That is the "this passage" that verse 5 refers to and what follows is Calvin's exposition of it.