Romans 9:18

Then therefore he has mercy on whom he will, and whom he will he hardens.

Romans 9:22-23

But if God, wishing to show forth his indignation and make his power known, endured with much longsuffering the vessels of indignation having been perfected unto 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
Then therefore he has mercy on whom he will, and whom he will he hardens.