Isaiah 37:8

So Rabshakeh returned, and found the king of Assyria warring against Libnah: for he had heard that he was departed from Lachish.

Cross-reference

2 Kings 19:8 gives the identical narrative of Rabshakeh finding the king at Libnah.

2 Kings 19:9 continues the account with Tirhakah's threat prompting a second message to Hezekiah.

2 Chronicles 32:9 parallels this account, specifically noting Sennacherib's siege of Lachish—confirming the historical setting.