Midrasch zu Jeschijahu 43:5

(Devarim, Ibid.) "and what is destined (for them) shall quickly befall them": When the L-rd brings punishment upon the nations, He "quickens" it upon them viz. (Habakkuk 1:8) "They (the avengers) will fly like an eagle, hastening to eat," and (Isaiah 5:19) "… who say: Let Him hasten, 'quicken' His act, so that we may see it. Let it approach and come near, etc." But when He brings afflictions upon Israel, they come gradually. How so? He relegated them to four exiles of subjugation. And, (in this connection, Jeremiah 1:8) "Do not fear … for I am with you."