John Calvin on Isaiah 37:8

8. And Rabshakeh having returned. He now declares how Rabshakeh, without doing anything, returned to his king, not to the same place where he had left him; for he understood that he had raised the siege of Lachish, and had departed into Egypt for the purpose of attacking Libnah. Some think that this city is Pelusium, others choose rather to assign it to Judea. It is, indeed, probable that, in consequence of a report that reached him about the approach of enemies, he moved his camp towards Egypt, that by meeting them he might prevent them from advancing. Though God restrained the violence of the tyrant by a new war, in order to give some relief to the Jews, yet he did not wish to conquer the tyrant by the hand of man, but only to shew openly and, as it were, to display on a theater his unconquerable pride; because, even when he was in great danger, he did not cease to vomit out the same blasphemies, as we shall soon see.