Great heaviness - Great grief.
Continual sorrow - The word rendered “continual” here must be taken in a popular sense. Not that he was literally all the time pressed down with this sorrow, but that whenever he thought on this subject, he had great grief; as we say of a painful subject, it is a source of constant pain. The cause of this grief, Paul does not expressly mention, though it is implied in what he immediately says. It was the fact that so large a part of the nation would be rejected, and cast off.