Romans 9:18

So he has mercy on anyone he pleases, and hardens the heart of anyone he pleases.

Romans 9:22-23

Then what if God, though he wanted to display his anger and show his power, has shown great patience toward the objects of his anger, already ripe for destruction,

Treasury of Scripture Knowledge

Summary

For it was of the LORD to harden their hearts, that they should come against Israel in battle, that he might destroy them utterly, and that they might have no favour, but that he might destroy them, as the LORD commanded Moses.

It was

Bible References

It was

Romans 9:18
So he has mercy on anyone he pleases, and hardens the heart of anyone he pleases.