While it is said, To day if ye will hear His voice, harden not your hearts, as in the provocation. – Hebrews 3:15

The wrath of God will produce no saving or softening effect. It has been suggested that a sinner, after suffering God’s wrath for a while, may repent, and so escape from it. But our observation and experience prove that the wrath of God never softened anybody’s heart yet, and we believe it never will. Those who are suffering divine wrath will go on to harden, and harden, and harden. The more they suffer, the more they will hate. The more they are punished, the more will they sin. The wrath of God abiding on you will produce no good results in you, but rather you shall go from evil to evil, further and further from the presence of God.

The reason why the wrath of God abides on an unbeliever is partly because all his other sins remain on him. There is no sin that shall damn the man who believes, and nothing can save the man who will not believe. God removes all sin the moment we believe, but while we believe not, fresh cords fasten upon us our transgressions. The sin of Judah is written as with an iron pen and graven with a point of a diamond. Nothing can release you from guilt while your heart remains at enmity with Jesus Christ your Lord.

Remember that God has never taken an oath, that I know of, against any class of persons, except unbelievers. “To whom swore He that they should not enter into His rest, but to them that believed not?” Continued unbelief God never will forgive, because His Word binds Him not to do so. Does He swear an oath, and shall He go back from it? It cannot be. O that you might have grace to relinquish your unbelief, and close in with the Gospel and be saved. ~ C.H. Spurgeon

https://www.blueletterbible.org/comm/spurgeon_charles/sermons/1012.cfm