What is the veil on Israel's heart?
The veil on Israel's heart is a national blindness that prevents them from seeing the truth when Moses is read. Although a believing remnant, the election, obtained it, the rest were blinded, and that blindness remains a veil over their heart so they cannot see through it.
Les explains that this is not about every individual Jew but about Israel nationally. Israel did not obtain what he sought, while the election—the small percentage of Jews who believed—obtained it. The rest were blinded, and that blinding is the veil on their heart according to II Corinthians. Even to this day, when Moses is read in the synagogues, the veil remains upon their heart, so they cannot see through it. Les also notes this follows the principle that grace cannot be mixed with law; grace must stand by itself.
What then? Israel hath not obtained that which he seeketh for; but the election hath obtained it, and the rest were blinded.
But even unto this day, when Moses is read, the vail is upon their heart.