Since Jesus is the Word, everything in the scriptures is from Him. Yet, in the account in John's gospel the quote from Isaiah is not spoken to the people by Jesus. John was inspired to include it to show the fulfillment of prophecy.
"Then Jesus said to them, “A little while longer the light is with you. Walk while you have the light, lest darkness overtake you; he who walks in darkness does not know where he is going. 36 While you have the light, believe in the light, that you may become sons of light.” These things Jesus spoke, and departed, and was hidden from them.
37 But although He had done so many signs before them, they did not believe in Him, 38 that the word of Isaiah the prophet might be fulfilled, which he spoke:
“Lord, who has believed our report?
And to whom has the arm of the Lord been revealed?”
39 Therefore they could not believe, because Isaiah said again:
40 “He has blinded their eyes and hardened their hearts,
Lest they should see with their eyes,
Lest they should understand with their hearts and turn,
So that I should heal them.”
41 These things Isaiah said when he saw His glory and spoke of Him."
So, I am still wondering... if as according to Calvinism, everyone is already incapable of believing in Jesus until they are first regenerated, why would God even need to harden anyone's heart at all so they could not believe?