The divine hammer!

Spurgeon, "Preach, Preach, Preach Everywhere"

You do not know who the elect are.

You do not know whose heart will be
broken by the divine hammer of truth.
But it is your responsibility to use the
divine hammer on the hard heart.

And as the gospel is preached it will
attract to itself, by its own power,
through the Holy Spirit, those whom
God has ordained unto eternal life.

"Is not my word like fire," declares the Lord,
"and like a hammer that breaks a rock in pieces?"
Jeremiah 23:29