Isaiah 37:8

So Rabshakeh returned
To the king of Assyria his master, to give him an account how things went at Jerusalem, and that he could get no direct answer from the king of Judah, and to consult with him what was proper to be done in the present situation of things; leaving the army before Jerusalem, under the command of the other two generals. For that he should take the army with him does not seem reasonable, when Hezekiah and his people were in such a panic on account of it; besides, the king of Assyria's letters to Hezekiah clearly suppose the army to be still at Jerusalem, or his menacing letters would have signified nothing; and after this the destruction of the Assyrian army before Jerusalem is related: and found the king of Assyria warring against Libnah;
a city in the tribe of Judah, ( Joshua 10:29 ) ( 15:42 ) , and lay nearer to Jerusalem than Lachish, where Rabshakeh left him; so that he seemed to be drawing his army towards that city, on which his heart was set. Josephus ^F21 makes him to be at this time besieging Pelusium, a city in Egypt, but wrongly; which has led some into a mistake that Libnah and Pelusium are the same: for he had heard that he was departed from Lachish;
where he was, when he sent him to Jerusalem, ( Isaiah 36:2 ) , having very probably taken it.